feat: export Markdown notes (ARQ/Redis) + backup/restore BDD — v0.5.2

- Volume data/ (bind mount ./data) remplace le volume uploads nommé
  data/notes/ → .md auto-générés, data/uploads/ → médias, data/backup/ → dumps
- Service Redis (redis:7-alpine) + worker ARQ (backend-worker)
- notes_markdown.py : frontmatter YAML + contenu + pièces jointes (liens relatifs)
  Nom : YYYY-MM-DD_slug-titre_shortid.md, rotation si titre modifié
- api/notes.py : publie export_note_markdown / remove_note_markdown sur Redis
  après chaque create / update / delete / add_attachment / delete_attachment
- api/admin.py : POST /backup, GET /backups, POST /restore/{filename} (pg_dump/pg_restore)
- Backend Dockerfile : postgresql-client ; requirements : arq==0.26.1
- ConfigPage : section "Base de données" avec sauvegarde + liste + restauration

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

backend/app/main.py

@@ -1,20 +1,28 @@
 from contextlib import asynccontextmanager
+from pathlib import Path
 from fastapi import FastAPI
 from fastapi.middleware.cors import CORSMiddleware
 from fastapi.staticfiles import StaticFiles
+from app.api.admin import router as admin_router
 from app.api.health import router as health_router
 from app.api.media import router as media_router
 from app.api.notes import router as notes_router
 from app.api.todos import router as todos_router
 from app.api.shopping import router as shopping_router
 from app.core.config import settings
+from app.core.redis import init_redis, close_redis
 from app.data.seed import run_seed
 
 
 @asynccontextmanager
 async def lifespan(app: FastAPI):
+    # Crée les dossiers data/ au démarrage
+    for subdir in ("uploads", "notes", "backup"):
+        Path(settings.data_dir, subdir).mkdir(parents=True, exist_ok=True)
     await run_seed()
+    await init_redis()
     yield
+    await close_redis()
 
 
 app = FastAPI(title="HomeHub API", version="0.1.0", lifespan=lifespan)
@@ -28,6 +36,7 @@ app.add_middleware(
 )
 
 app.include_router(health_router, prefix="/api")
+app.include_router(admin_router, prefix="/api/admin")
 app.include_router(media_router, prefix="/api/media")
 app.include_router(notes_router, prefix="/api/notes")
 app.include_router(todos_router, prefix="/api/todos")