feat: migrate desktop app from Electron to Tauri v2

[balcsida]

Summary

Migrate the Goose desktop application from Electron v40 to Tauri v2, replacing the Node.js main process with a Rust backend while preserving the existing React 19 + Vite frontend through a compatibility bridge pattern.

Architecture

┌─────────────────────────────────────────┐
│  Existing React 19 + Vite Frontend      │
│  (40+ files unchanged)                  │
├─────────────────────────────────────────┤
│  tauri-bridge.ts                        │
│  (drop-in window.electron shim)         │
├─────────────────────────────────────────┤
│  Tauri Rust Backend (~1,600 LOC)        │
│  8 modules / 42 IPC commands            │
├─────────────────────────────────────────┤
│  17 Tauri Plugins                       │
│  (dialog, fs, shell, updater, etc.)     │
└─────────────────────────────────────────┘

Key changes

• Rust backend (src-tauri/src/): 8 modules replacing the 2,394-line Electron main.ts
  • lib.rs - App setup, plugin init, lifecycle hooks
  • commands.rs - 42 IPC command handlers (settings, file ops, window mgmt, etc.)
  • goosed.rs - Backend process management with binary discovery and health polling
  • tray.rs / menu.rs - System tray and application menu
  • settings.rs - Persistent settings via JSON
  • wakelock.rs - Platform-specific sleep prevention (IOKit/macOS, SetThreadExecutionState/Windows)
  • dock.rs - macOS dock integration via Cocoa/objc
• Compatibility bridge (tauri-bridge.ts): Drop-in window.electron shim so existing frontend files work without modification
• 17 Tauri plugins: dialog, fs, shell, notification, global-shortcut, deep-link, updater, window-state, opener, store, process, log, clipboard, http, autostart, single-instance
• Build config: Tauri-specific Vite config, npm scripts (tauri:dev, tauri:build), sidecar bundling
• Side-by-side: Electron files restored for coexistence during transition period

Benefits over Electron

• Smaller bundle: Uses system WebView instead of bundling Chromium (~150MB savings)
• Lower memory: Rust backend vs Node.js main process
• Native performance: Rust-powered IPC, file operations, and process management
• Rust alignment: Keeps the entire stack in Rust, matching the existing goose codebase

Type of Change

• Feature
• Refactor / Code quality
• Build / Release

AI Assistance

• This PR was created or reviewed with AI assistance

Testing

Automated (46 unit tests):

• Settings: serialization/deserialization roundtrip, defaults, camelCase field mapping, missing field handling
• Commands: URL encoding (spaces, ampersands, equals, hashes, percent), recipe SHA-256 hashing (determinism, format, uniqueness), file operations (read/write/list with temp dirs), deep link classification
• Goosed: fatal error detection, environment variable construction, state initialization

Manual:

• Verified npm run tauri:dev compiles (582 Rust crates + Vite frontend)
• Confirmed goosed backend starts and connects
• Confirmed Tauri app window opens and renders the React frontend
• Verified window dragging via data-tauri-drag-region
• Tested system tray and application menu functionality
• Tested macOS dock menu, traffic light positioning, transparent titlebar

Known Limitations

• Tray update icon swap needs further testing
• Linux wakelock is a stub (D-Bus integration planned)
• No CI pipeline for Tauri builds yet

Related Issues

Closes #7332

Screenshots/Demos

Tauri Goose

Electron Goose