fix: avatars persistant — route fichier + couleur en DB + sidebar affichage

- Route manquante GET /api/settings/avatar/{filename} → sert le fichier uploadé
  (résout le 404 sur l'image uploadée)
- Colonne avatar_color ajoutée à users (migration ALTER TABLE try/except)
- set_avatar_color sauvegarde la couleur dans la DB (pas seulement local)
- _sidebar_data() lit avatar_url + avatar_color depuis la DB
- Sidebar avatar: fond coloré quand pas d'image, image quand uploadée
  avec background-image:url() + initiale en fallback

app/routers/dashboard.py

@@ -36,6 +36,19 @@ def _sidebar_data(request: Request, repos: list[dict]) -> dict:
     ws = user.get("login", "Bruno") if user else "Bruno"
     initial = ws[0].upper() if ws else "B"
 
+    # Get avatar info from DB
+    avatar_url = ""
+    avatar_color = "#3A3A3A"
+    if user:
+        try:
+            with get_conn() as conn:
+                row = conn.execute("SELECT avatar_url, avatar_color FROM users WHERE id = ?", (user["id"],)).fetchone()
+                if row:
+                    avatar_url = row["avatar_url"] or ""
+                    avatar_color = row["avatar_color"] or "#3A3A3A"
+        except Exception:
+            pass
+
     recent_pages = []
     for repo in repos[:10]:
         full_name = repo.get("full_name", "")
@@ -76,6 +89,8 @@ def _sidebar_data(request: Request, repos: list[dict]) -> dict:
         "favorite_pages": [],
         "shared_pages": [],
         "user": user,
+        "avatar_url": avatar_url,
+        "avatar_color": avatar_color,
         "workspace_key": "",
     }
 
@@ -1125,6 +1140,17 @@ async def upload_avatar(request: Request):
     return {"avatar_url": avatar_url}
 
 
+@router.get("/api/settings/avatar/{filename:path}")
+async def serve_avatar_file(filename: str):
+    """Serve an uploaded avatar image file."""
+    from fastapi.responses import FileResponse
+    from pathlib import Path
+    filepath = Path("/data/avatars") / filename
+    if not filepath.is_file():
+        return JSONResponse({"error": "Not found"}, status_code=404)
+    return FileResponse(filepath)
+
+
 @router.get("/api/avatar/{user_id:int}")
 async def get_avatar(user_id: int):
     """Redirect to the user's avatar."""
@@ -1137,15 +1163,14 @@ async def get_avatar(user_id: int):
 
 @router.post("/api/settings/avatar-color")
 async def set_avatar_color(request: Request):
-    """Set the user's avatar background color (for initial-based avatars)."""
-    import json
+    """Set the user's avatar background color."""
     body = await request.json()
     color = body.get("color", "#3A3A3A")
     user = SessionManager.decode_session(request.cookies.get("flowdeck_session", ""))
     if not user:
         return {"error": "Not authenticated"}, 401
     with get_conn() as conn:
-        conn.execute("UPDATE users SET avatar_url = '' WHERE id = ?", (user["id"],))
+        conn.execute("UPDATE users SET avatar_url = '', avatar_color = ? WHERE id = ?", (color, user["id"]))
         conn.commit()
     return {"status": "ok", "color": color}