feat!: vendor display-dj-cli, drop HTTP sidecar (v7.0.0)

BREAKING CHANGE: collapses the bundled display-dj-server HTTP sidecar
into in-process Rust calls. The platform code (DDC/CI, gamma, WMI,
DisplayServices, dark mode, volume, wallpaper, slideshow) is now
vendored under src-tauri/src/core/ and Tauri commands invoke it
directly via spawn_blocking. There is no separate process to manage,
no port discovery, no HTTP, no externalBin, no bundled binaries, no
runtime dependency on display-dj-cli releases.

Architecture
- core/{mod,macos,windows,linux,theme,volume,wallpaper,display}.rs
  vendored from display-dj-cli main.rs + platform files (~1100 LOC).
  core::PlatformImpl is a cfg-gated alias to the right platform type.
- src/{display,dark_mode,volume,wallpaper}.rs are now thin Tauri-cmd
  wrappers; CPU-bound calls wrapped in spawn_blocking to keep async
  signatures (macOS tray pitfall).
- tray.rs::execute_command dispatches everything in-process;
  build_command_url is now cfg(test)-only and always returns None.
- AppState lost sidecar_child. lib.rs lost SERVER_PORT, server_port,
  kill_stale_sidecars, find_available_port, wait_for_server,
  fetch_debug_on_startup, the sidecar spawn block, and the
  RunEvent::Exit child.kill block. fetch_initial_tray_state now
  reads core::theme/volume directly.

Removed
- tauri-plugin-shell (Cargo.toml + capabilities/default.json)
- src-tauri/binaries/ (6 prebuilt server binaries)
- externalBin in tauri.conf.json
- displayDjCliVersion in package.json
- build.rs sidecar download fallback (now just tauri_build::build()
  + the existing expose_app_version helper)

Added Cargo deps
- ddc 0.2 (top-level)
- ddc-macos 0.2, libc 0.2 (macOS)
- ddc-winapi 0.2, winapi 0.3 (Windows); Win32_Devices_Display feature
  on the existing windows crate

Tests
- cargo test --lib: 229 passed
- npm test: 70 passed
- frontend build: clean

Docs
- CLAUDE.md, README.md, CONTRIBUTING.md rewritten to describe the
  in-process model. New "Vendored platform core" section in
  CONTRIBUTING.md replaces the old sidecar setup steps.

Net diff: +623 / -1739 across 25 files.

Co-Authored-By: Claude Opus 4 (1M context) <noreply@anthropic.com>

Author: synle

CLAUDE.md

@@ -50,7 +50,6 @@ A cross-platform desktop system tray app for controlling monitor brightness, con
 - **Settings panel** -- tabbed UI (General + Tiling) with auto-save. Configure brightness, contrast, monitors, night mode, snap zones, exposé grid size, layout strategy, and launch at login
 - **About / Update check** -- "About Display DJ" in the tray menu shows current version, latest GitHub release, engine, platform, build date, and homepage. Green "Up to date" or orange "Update available" badge with download link. macOS section includes quarantine fix and Accessibility settings commands
 - **System tray app** -- lives in your menu bar / system tray with no dock or taskbar clutter
-- **Single-instance** -- only one copy of Display DJ runs at a time. If you accidentally launch it twice (e.g. autostart racing a manual launch), the duplicate exits silently so you never end up with multiple tray icons or competing sidecars
 
 ## Download & Install
 
@@ -329,9 +328,9 @@ This recursively clears the quarantine flag so macOS allows the app to run. You
 
 ## Tech Stack
 
-[Tauri v2](https://v2.tauri.app/) (Rust) + React 19 + TypeScript + Vite 6 + [display-dj CLI](https://github.com/synle/display-dj-cli)
+[Tauri v2](https://v2.tauri.app/) (Rust) + React 19 + TypeScript + Vite 6.
 
-Display and dark mode operations are handled by the bundled [display-dj CLI](https://github.com/synle/display-dj-cli) sidecar -- no external tools need to be installed on macOS or Windows.
+All platform code (DDC/CI, gamma, WMI, DisplayServices, dark mode, volume, wallpaper) lives in-process inside the Rust backend under `src-tauri/src/core/`. There is no external sidecar or helper binary -- macOS and Windows need no extra tools installed; Linux needs the system packages listed in the install section above.
 
 ## Contributing
 

CONTRIBUTING.md

@@ -2,7 +2,6 @@
   "name": "display-dj",
   "version": "0.0.0",
   "description": "Cross-platform desktop app for monitor brightness, contrast, and dark mode control",
-  "displayDjCliVersion": "v2.2.2",
   "scripts": {
     "dev": "vite",
     "build": "tsc && vite build",

README.md

@@ -17,7 +17,6 @@ serde_json = "1"
 tauri = { version = "2", features = ["tray-icon"] }
 tauri-plugin-autostart = "2"
 tauri-plugin-global-shortcut = "2"
-tauri-plugin-shell = "2"
 serde = { version = "1", features = ["derive"] }
 serde_json = "1"
 dirs = "6"
@@ -30,10 +29,13 @@ keepawake = "0.6"
 tauri-plugin-dialog = "2"
 md5 = "0.7"
 zip = "2"
+ddc = "0.2"
 
 [target.'cfg(target_os = "macos")'.dependencies]
 objc = "0.2"
 block = "0.1"
+ddc-macos = "0.2"
+libc = "0.2"
 
 [target.'cfg(target_os = "linux")'.dependencies]
 x11rb = { version = "0.13", features = ["randr"] }
@@ -46,7 +48,10 @@ windows = { version = "0.58", features = [
     "Win32_UI_HiDpi",
     "Win32_UI_WindowsAndMessaging",
     "Win32_System_Threading",
+    "Win32_Devices_Display",
 ] }
+ddc-winapi = "0.2"
+winapi = { version = "0.3", features = ["wingdi", "windef"] }
 
 [profile.release]
 panic = "abort"