feat(boot): écran de chargement inline + staging backend/frontend pour le bundle desktop

- frontend/index.html : splash #boot-splash 100% inline (CSS+JS), scripts CDN en defer pour ne pas bloquer le premier paint
- frontend/js/app.js : signale le boot terminé via __OBSIGATE_BOOTED (try/finally)
- desktop/src/main.rs : met à jour le statut du splash avant la redirection vers le backend
- ci: stage backend/ + frontend/ sous desktop/ avant tauri build (resources backend/** et frontend/**) dans desktop-build.yml et build-linux.sh
- desktop/gen/schemas/windows-schema.json : régénéré (permissions store/updater)
- docs: README, README.fr, ROADMAP

.gitea/workflows/desktop-build.yml

@@ -29,6 +29,12 @@ jobs:
           cd desktop/python-embed
           ./python.exe -m pip install --no-cache-dir -r ../../backend/requirements.txt
 
+      - name: Stage backend + frontend for bundle
+        working-directory: desktop
+        run: |
+          xcopy /E /I /Q /Y "..\backend" "backend"
+          xcopy /E /I /Q /Y "..\frontend" "frontend"
+
       - name: Build MSI
         working-directory: desktop
         run: cargo tauri build --bundles msi
@@ -68,6 +74,12 @@ jobs:
           source desktop/python-embed/venv/bin/activate
           pip install -r backend/requirements.txt
 
+      - name: Stage backend + frontend for bundle
+        working-directory: desktop
+        run: |
+          cp -r ../backend backend
+          cp -r ../frontend frontend
+
       - name: Build AppImage
         working-directory: desktop
         run: cargo tauri build --bundles appimage