feat: Add Linux support documentation

This commit introduces two new files:

- LINUX_AUDIO.md: Documents the current state of audio support on Linux.
- LINUX_SUPPORT.md: Provides a comprehensive overview of missing features for full Linux support.

Author: PythonTilk

LINUX_AUDIO.md

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+# Linux Audio Implementation Status
+
+This document outlines the current status of the audio implementation for Linux in this project.
+
+## Current Implementation
+
+The current implementation in `crates/audio/src/speaker/linux.rs` is a **mock implementation**. It does not capture any actual audio from the system. Instead, it generates a stream of silence.
+
+## Microphone Usage Detection
+
+The application uses the `pactl` command-line tool to detect if a microphone is currently in use by any application. This is implemented in `crates/detect/src/mic/linux.rs`.
+
+This indicates that there is some level of interaction with the PulseAudio sound server, but it is limited to monitoring and does not include audio capture.
+
+## Audio Processing Pipeline
+
+The application has a sophisticated audio processing pipeline that is managed by a state machine in `plugins/listener/src/fsm.rs`. The pipeline is as follows:
+
+1.  **Audio Input:**
+    *   Microphone audio is captured using the `cpal` crate, which provides a cross-platform API for audio I/O.
+    *   Speaker audio is captured using a platform-specific implementation. **On Linux, this is currently a mock implementation that generates silence.**
+
+2.  **Processing:**
+    *   Both the microphone and speaker audio streams are resampled to 16kHz.
+    *   Acoustic Echo Cancellation (AEC) is performed using the `hypr_aec` crate. The speaker audio is used as the reference signal to remove echo from the microphone audio.
+    *   The AEC-processed microphone audio and the speaker audio are mixed together.
+    *   Audio levels (amplitude) are calculated and sent to the frontend for visualization.
+
+3.  **Output:**
+    *   The mixed audio is sent to the `owhisper` service for speech-to-text transcription.
+    *   In debug mode, the raw microphone, raw speaker, and mixed audio streams are saved to `.wav` files for debugging purposes.
+
+## Missing Features
+
+The following features are missing for a complete Linux audio implementation:
+
+*   **Actual audio capture:** The primary missing feature is the ability to capture system audio. The current implementation only provides a silent stream.
+*   **PipeWire support:** There is no integration with the PipeWire audio server. A full implementation would require using the PipeWire API to capture audio.
+*   **PulseAudio support:** There is no integration with the PulseAudio audio server. A full implementation would require using the PulseAudio API to capture audio.
+*   **ALSA support:** While ALSA is mentioned in the code comments, there is no actual implementation that uses ALSA to capture audio.
+
+## Next Steps
+
+To have a functional audio implementation on Linux, the following steps need to be taken:
+
+1.  Decide on the primary audio backend to support. PipeWire is the modern choice, but PulseAudio and ALSA are still relevant for compatibility.
+2.  Implement audio capture using the chosen audio backend's API.
+3.  Provide a mechanism to select the audio backend at runtime or compile time.

LINUX_SUPPORT.md

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+# Linux Support Status
+
+This document outlines the current status of Linux support in the Hyprnote application, highlighting areas that are missing or incomplete.
+
+## 1. Speaker Audio Capture
+
+**This is the most critical missing feature for full Linux support.**
+
+The current implementation for speaker audio capture on Linux is a mock that only generates silence. The file `crates/audio/src/speaker/linux.rs` needs to be implemented to capture system audio using a native Linux audio backend.
+
+**Recommended solutions:**
+
+*   **PipeWire:** The modern and preferred audio server on Linux.
+*   **PulseAudio:** A widely used and still relevant audio server.
+*   **ALSA:** The underlying audio API, which can be used for broader compatibility.
+
+## 2. Notifications
+
+The `hypr_notification2` crate, which is responsible for handling desktop notifications, has incomplete support for Linux.
+
+*   **Basic Notifications:** Basic notifications may work if the underlying `wezterm` crate has Linux support.
+*   **Missing Features:**
+    *   **Permission Handling:** The ability to request notification permissions from the user is not implemented for Linux.
+    *   **Settings Integration:** The functionality to open the system's notification settings is not implemented for Linux.
+
+## 3. Desktop Integration
+
+### 3.1. Application Menu
+
+The main application menu is customized for macOS to provide a more native look and feel. This includes adding "About Hyprnote" and "New Note" items to the application menu. This level of integration is missing for Linux.
+
+### 3.2. Window Decorations
+
+The `plugins/windows` crate contains platform-specific code for window decorations on macOS and Windows.
+
+*   **macOS:** Uses a title bar with an overlay style and a hidden title.
+*   **Windows:** Uses borderless windows.
+*   **Linux:** Lacks specific window decoration configurations, which may result in an inconsistent and less polished user experience. The application will use the default window decorations provided by the user's window manager.
+
+## 4. Build and Packaging
+
+While not explicitly investigated, it's important to ensure that the application can be easily built and packaged for various Linux distributions. This includes:
+
+*   **Dependencies:** Ensuring that all required dependencies are available on common Linux distributions.
+*   **Packaging Formats:** Providing packages in common formats like `.deb` (for Debian/Ubuntu), `.rpm` (for Fedora/CentOS), and `AppImage` (for distribution-agnostic use).
+
+## 5. macOS-Specific Features and Implementations
+
+Several features and implementations in the Hyprnote application are specific to macOS. These features will not work on Linux, and in some cases, the application may not behave as expected.
+
+### 5.1. Apple Calendar Integration
+
+The `tauri-plugin-apple-calendar` is **macOS-specific** and cannot be used on Linux. This is because it relies on macOS-specific technologies to interact with the Calendar and Contacts applications.
+
+The reasons for this include:
+
+*   **`osascript`:** The plugin uses `osascript` to execute AppleScript for interacting with the Calendar application.
+*   **`open x-apple.systempreferences`:** The plugin uses macOS-specific URL schemes to open the System Preferences to the correct privacy settings.
+*   **`hypr_calendar_apple` crate:** The plugin uses the `hypr_calendar_apple` crate, which is a wrapper around Apple's native frameworks for accessing calendar and contact data.
+*   **`tccutil`:** The plugin uses the `tccutil` command-line tool to manage calendar and contacts permissions, which is specific to macOS.
+
+### 5.2. AI/ML Acceleration
+
+The application uses Apple's **Metal** and **Core ML** frameworks for hardware-accelerated AI/ML tasks on macOS. This is enabled through the `llm-metal`, `stt-metal`, and `stt-coreml` features. While the application may fall back to CPU-based processing on Linux, it will not have the same level of performance as on Apple hardware.
+
+### 5.3. Autostart
+
+The autostart feature is implemented using `launchd` on macOS. For the application to autostart on Linux, a different implementation is required, such as creating a `.desktop` file in the `~/.config/autostart/` directory.
+
+### 5.4. Microphone and System Audio Permissions
+
+The permission handling for microphone and system audio access is heavily reliant on macOS-specific APIs and command-line tools.
+
+*   **`check_microphone_access`:** On Linux, this function is a workaround that tries to open the microphone to see if it's available, which is not a reliable permission check.
+*   **`request_microphone_access`:** On Linux, this function also tries to open the microphone, which may or may not trigger a system-level permission prompt.
+*   **`open_microphone_access_settings` and `open_system_audio_access_settings`:** These functions will not work on Linux as they use macOS-specific URLs.
+*   **`check_system_audio_access`:** This function relies on the `hypr_tcc` crate, which is entirely macOS-specific and always returns `true` on Linux.
+
+### 5.5. TCC (Transparency, Consent, and Control)
+
+The `hypr_tcc` crate, which is used for managing permissions, is entirely macOS-specific and has no functionality on Linux.
+
+### 5.6. Email Integration
+
+The application uses the native macOS email client to send emails. This is implemented in the `crates/email` crate, which uses the `NSSharingService` class. This functionality will be missing on Linux. To provide a similar feature on Linux, a different approach would be needed, such as opening a `mailto:` URL or using a library that can communicate with common Linux email clients.
+
+### 5.7. Application and Browser Detection
+
+The application uses macOS-specific APIs to detect running applications and the frontmost browser window. This is used for features like automatically detecting meetings.
+
+*   **`crates/detect/src/app/macos.rs`:** Uses `ns::RunningApp` and `ns::Workspace` to detect running applications.
+*   **`crates/detect/src/browser/macos.rs`:** Uses `objc2_foundation::NSURL` and `objc2_app_kit::NSWorkspace` to get the URL of the frontmost browser window.
+
+A Linux-specific implementation would be needed to provide similar functionality. This could involve using the `/proc` filesystem or a library like `libprocps`.
+
+## 6. Conclusion
+
+To achieve full Linux support, the following tasks need to be prioritized:
+
+1.  **Implement speaker audio capture** in `crates/audio/src/speaker/linux.rs`.
+2.  **Add full notification support** for Linux in the `hypr_notification2` crate, including permission handling and settings integration.
+3.  **Improve desktop integration** by customizing the application menu and window decorations for a more native Linux experience.
+4.  **Ensure robust build and packaging** for various Linux distributions.