feat(db-hardening): Add database persistence, backups, and MinIO assets storage

Database Hardening:
- Add docker-compose.db.yml with persistent PostgreSQL volume
- Add automatic DB backups every 12h (7 days, 4 weeks, 6 months retention)
- Add MinIO S3-compatible storage for assets

Assets Migration:
- Add MinIO client (lib/assets_client.py) for upload/delete
- Update upload endpoint to use MinIO (with local fallback)
- Add migration 043_asset_urls_to_text.sql for full HTTPS URLs
- Simplify normalizeAssetUrl for S3 URLs

Recovery:
- Add seed_full_city_reset.py for emergency city recovery
- Add DB_RESTORE.md with backup restore instructions
- Add SEED_RECOVERY.md with recovery procedures
- Add INFRA_ASSETS_MINIO.md with MinIO setup guide

Task: TASK_PHASE_DATABASE_HARDENING_AND_ASSETS_MIGRATION_v1

services/city-service/routes_city.py

@@ -14,6 +14,14 @@ import uuid
 from PIL import Image
 import shutil
 
+# MinIO assets client
+try:
+    from lib.assets_client import upload_asset as minio_upload_asset
+    MINIO_AVAILABLE = True
+except ImportError:
+    MINIO_AVAILABLE = False
+    logger.warning("MinIO client not available, falling back to local storage")
+
 from models_city import (
     CityRoomRead,
     CityRoomCreate,
@@ -339,24 +347,69 @@ async def upload_asset(
             
         processed_bytes, thumb_bytes = process_image(content, max_size=max_size, force_square=force_square)
         
-        # Save to disk
+        # Map type to prefix
+        type_to_prefix = {
+            'microdao_logo': 'microdao/logo',
+            'microdao_banner': 'microdao/banner',
+            'room_logo': 'rooms/logo',
+            'room_banner': 'rooms/banner',
+            'agent_avatar': 'agents/avatar',
+        }
+        prefix = type_to_prefix.get(type, 'uploads')
+        
+        # Upload to MinIO if available, otherwise fallback to local storage
+        if MINIO_AVAILABLE:
+            try:
+                # Upload processed image
+                processed_file = io.BytesIO(processed_bytes)
+                processed_url = minio_upload_asset(
+                    processed_file,
+                    content_type="image/png",
+                    prefix=prefix,
+                    filename=file.filename
+                )
+                
+                # Upload thumbnail if exists
+                thumb_url = None
+                if thumb_bytes:
+                    thumb_file = io.BytesIO(thumb_bytes)
+                    thumb_url = minio_upload_asset(
+                        thumb_file,
+                        content_type="image/png",
+                        prefix=f"{prefix}/thumb",
+                        filename=file.filename
+                    )
+                
+                return {
+                    "original_url": processed_url,
+                    "processed_url": processed_url,
+                    "thumb_url": thumb_url or processed_url
+                }
+            except Exception as e:
+                logger.warning(f"MinIO upload failed, falling back to local: {e}")
+                # Fall through to local storage
+        
+        # Fallback: Save to local disk
         filename = f"{uuid.uuid4()}.png"
         filepath = f"static/uploads/{filename}"
         thumb_filepath = f"static/uploads/thumb_{filename}"
         
+        os.makedirs("static/uploads", exist_ok=True)
+        
         with open(filepath, "wb") as f:
             f.write(processed_bytes)
             
-        with open(thumb_filepath, "wb") as f:
-            f.write(thumb_bytes)
-            
+        if thumb_bytes:
+            with open(thumb_filepath, "wb") as f:
+                f.write(thumb_bytes)
+        
         # Construct URLs
-        base_url = "/static/uploads"
+        base_url = "/api/static/uploads"
         
         return {
             "original_url": f"{base_url}/{filename}",
             "processed_url": f"{base_url}/{filename}",
-            "thumb_url": f"{base_url}/thumb_{filename}"
+            "thumb_url": f"{base_url}/thumb_{filename}" if thumb_bytes else f"{base_url}/{filename}"
         }
         
     except Exception as e: