Discord rich presence + Low latency mode

[zortos293]

This pull request introduces several new features and enhancements focused on improving the user experience for Windows users, Discord integration, and streaming controls. The most notable changes are the addition of native mouse capture and Escape key blocking for Windows, enhanced Discord Rich Presence with optional streaming stats, and various UI and configuration improvements.

Windows-native streaming enhancements:

• Added src-tauri/src/keyboard_hook.rs: Implements an OS-level keyboard hook to block the Escape key during streaming on Windows, preventing accidental exit from pointer lock. Includes Tauri commands for toggling and querying the block state.
• Added src-tauri/src/mouse_capture.rs: Implements native mouse capture on Windows using raw input APIs, bypassing browser pointer lock and its "press Esc" message. Provides Tauri commands for capturing/releasing the mouse and querying movement deltas.

Discord Rich Presence improvements:

• Updated Discord integration to support displaying streaming stats (resolution, FPS, latency) in the presence, controlled by a new "Show Stats in Discord" setting. Added a new Tauri command for updating stats during gameplay, and replaced branding from "GeForce NOW" to "OpenNOW" with a GitHub button in the presence. [1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] [12] [13] [14] [15]

Settings and UI changes:

• Added a new checkbox in the settings UI for enabling Discord stats display, and updated the settings handling in both backend (Settings struct) and frontend (Settings interface and state management). [1] [2] [3] [4] [5] [6] [7] [8]
• Updated the streaming UI state to track region, last Discord update time, and game start time for improved presence updates.

Feature completion:

• Marked "Multi-region ping display" as completed in the project README.