feat: Tauri desktop shell — Rust backend + config files + build scripts

- desktop/Cargo.toml: Tauri + plugins (dialog, notification, fs, updater)
- desktop/tauri.conf.json: Windows (.msi/.nsis) + Linux (.deb/.AppImage) config
- desktop/src/main.rs: spawn Python backend, health check, tray icon, commands
- desktop/build.rs: Tauri build hook
- desktop/python-embed/sidecar.py: uvicorn launcher with port auto-detect
- build-windows.bat: automated Windows build with Python embed download
- build-linux.sh: automated Linux build with venv
- desktop/README.md: architecture doc + usage guide
- desktop/validate-structure.sh: CI validation script
- ROADMAP.md: #77 Tauri Desktop section added

desktop/build-windows.bat

@@ -0,0 +1,61 @@
+@echo off
+REM ============================================================
+REM  ObsiGate Desktop — Build Windows (.msi + .exe)
+REM  Prérequis : Rust, Tauri CLI, NSIS, Python 3.11 embed
+REM ============================================================
+setlocal enabledelayedexpansion
+
+echo ========================================
+echo   ObsiGate Desktop — Build Windows
+echo ========================================
+echo.
+
+REM ── 1. Vérifier les prérequis ─────────────────────────────────
+echo [1/6] Verifying prerequisites...
+where cargo >nul 2>&1 || (echo ❌ Rust/Cargo not found. Install from https://rustup.rs & exit /b 1)
+where tauri >nul 2>&1 || cargo install tauri-cli
+echo ✅ Rust + Tauri OK
+
+REM ── 2. Préparer Python 3.11 embed ─────────────────────────────
+echo [2/6] Preparing Python embed...
+if not exist "python-embed\python.exe" (
+    echo 📥 Downloading Python 3.11 embed...
+    curl -L -o python-embed.zip "https://www.python.org/ftp/python/3.11.15/python-3.11.15-embed-amd64.zip"
+    powershell Expand-Archive -Path python-embed.zip -DestinationPath python-embed\
+    del python-embed.zip
+    
+    REM Enable pip in embedded Python
+    echo import site >> python-embed\python311._pth
+    
+    REM Install dependencies
+    python-embed\python.exe -m pip install --no-cache-dir -r ..\backend\requirements.txt
+)
+echo ✅ Python embed ready
+
+REM ── 3. Copier le frontend ─────────────────────────────────────
+echo [3/6] Copying frontend...
+if exist "frontend-static" rmdir /s /q "frontend-static"
+xcopy /E /I /Q "..\frontend" "frontend-static"
+echo ✅ Frontend copied
+
+REM ── 4. Mettre à jour les icônes ───────────────────────────────
+echo [4/6] Generating icons...
+REM Placeholder — will use tauri icon generator when icons are ready
+echo ✅ Icons OK (using defaults)
+
+REM ── 5. Build Tauri ────────────────────────────────────────────
+echo [5/6] Building Tauri application...
+cargo tauri build --target x86_64-pc-windows-msvc --bundles msi,nsis
+if errorlevel 1 (
+    echo ❌ Build failed!
+    exit /b 1
+)
+echo ✅ Build successful
+
+REM ── 6. Signer (optionnel) ─────────────────────────────────────
+echo [6/6] Results:
+dir /b target\release\bundle\msi\*.msi 2>nul
+dir /b target\release\bundle\nsis\*.exe 2>nul
+echo.
+echo ✅ Done! Check target\release\bundle\
+endlocal