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/api/admin.py

@@ -0,0 +1,95 @@
+import asyncio
+import os
+from datetime import datetime
+from pathlib import Path
+from urllib.parse import urlparse
+
+from fastapi import APIRouter, HTTPException
+
+from app.core.config import settings
+
+router = APIRouter()
+
+
+def _pg_env() -> dict:
+    url = urlparse(settings.database_url.replace("+asyncpg", ""))
+    env = os.environ.copy()
+    env["PGPASSWORD"] = url.password or ""
+    return env, url
+
+
+@router.post("/backup")
+async def create_backup():
+    backup_dir = settings.backup_path
+    backup_dir.mkdir(parents=True, exist_ok=True)
+
+    timestamp = datetime.now().strftime("%Y-%m-%d_%H%M")
+    filename = f"homehub_{timestamp}.dump"
+    filepath = backup_dir / filename
+
+    env, url = _pg_env()
+    proc = await asyncio.create_subprocess_exec(
+        "pg_dump", "-Fc",
+        "-h", url.hostname or "db",
+        "-p", str(url.port or 5432),
+        "-U", url.username or "homehub",
+        "-d", (url.path or "/homehub").lstrip("/"),
+        "-f", str(filepath),
+        env=env,
+        stderr=asyncio.subprocess.PIPE,
+    )
+    _, stderr = await proc.communicate()
+    if proc.returncode != 0:
+        raise HTTPException(500, f"Échec du backup : {stderr.decode()}")
+
+    stat = filepath.stat()
+    return {
+        "filename": filename,
+        "size": stat.st_size,
+        "created_at": datetime.now().isoformat(),
+    }
+
+
+@router.get("/backups")
+async def list_backups():
+    backup_dir = settings.backup_path
+    if not backup_dir.exists():
+        return []
+    files = sorted(backup_dir.glob("*.dump"), key=lambda f: f.stat().st_mtime, reverse=True)
+    return [
+        {
+            "filename": f.name,
+            "size": f.stat().st_size,
+            "created_at": datetime.fromtimestamp(f.stat().st_mtime).isoformat(),
+        }
+        for f in files
+    ]
+
+
+@router.post("/restore/{filename}")
+async def restore_backup(filename: str):
+    # Sécurité : interdit les chemins relatifs
+    if "/" in filename or ".." in filename or not filename.endswith(".dump"):
+        raise HTTPException(400, "Nom de fichier invalide")
+
+    filepath = settings.backup_path / filename
+    if not filepath.exists():
+        raise HTTPException(404, "Fichier introuvable")
+
+    env, url = _pg_env()
+    proc = await asyncio.create_subprocess_exec(
+        "pg_restore", "--clean", "--if-exists", "--no-owner", "--no-privileges",
+        "-h", url.hostname or "db",
+        "-p", str(url.port or 5432),
+        "-U", url.username or "homehub",
+        "-d", (url.path or "/homehub").lstrip("/"),
+        str(filepath),
+        env=env,
+        stderr=asyncio.subprocess.PIPE,
+    )
+    _, stderr = await proc.communicate()
+    # pg_restore retourne 1 pour des warnings non-fatals (DROP IF EXISTS sur objets manquants)
+    if proc.returncode not in (0, 1):
+        raise HTTPException(500, f"Échec de la restauration : {stderr.decode()}")
+
+    return {"message": "Restauration réussie"}