feat: asset-based image/video sources, notification sounds, UI improvements

- Replace URL-based image_source/url fields with image_asset_id/video_asset_id
  on StaticImagePictureSource and VideoCaptureSource (clean break, no migration)
- Resolve asset IDs to file paths at runtime via AssetStore.get_file_path()
- Add EntitySelect asset pickers for image/video in stream editor modal
- Add notification sound configuration (global sound + per-app overrides)
- Unify per-app color and sound overrides into single "Per-App Overrides" section
- Persist notification history between server restarts
- Add asset management system (upload, edit, delete, soft-delete)
- Replace emoji buttons with SVG icons throughout UI
- Various backend improvements: SQLite stores, auth, backup, MQTT, webhooks

server/src/wled_controller/storage/database.py

@@ -55,9 +55,19 @@ _ENTITY_TABLES = [
     "color_strip_processing_templates",
     "gradients",
     "weather_sources",
+    "assets",
 ]
 
 
+_VALID_TABLES = frozenset(_ENTITY_TABLES) | {"settings", "schema_version"}
+
+
+def _check_table(table: str) -> None:
+    """Raise ValueError if *table* is not a known entity table."""
+    if table not in _VALID_TABLES:
+        raise ValueError(f"Invalid table name: {table!r}")
+
+
 class Database:
     """Thread-safe SQLite connection wrapper with WAL mode.
 
@@ -169,6 +179,7 @@ class Database:
 
         Returns list of dicts parsed from the ``data`` JSON column.
         """
+        _check_table(table)
         with self._lock:
             rows = self._conn.execute(
                 f"SELECT id, data FROM [{table}]"
@@ -187,6 +198,7 @@ class Database:
 
         Skipped silently when writes are frozen.
         """
+        _check_table(table)
         if _writes_frozen:
             return
         json_data = json.dumps(data, ensure_ascii=False)
@@ -202,6 +214,7 @@ class Database:
 
         Skipped silently when writes are frozen.
         """
+        _check_table(table)
         if _writes_frozen:
             return
         with self._lock:
@@ -215,6 +228,7 @@ class Database:
 
         Skipped silently when writes are frozen.
         """
+        _check_table(table)
         if _writes_frozen:
             return
         with self._lock:
@@ -226,6 +240,7 @@ class Database:
 
         Skipped silently when writes are frozen.
         """
+        _check_table(table)
         if _writes_frozen:
             return
         with self._lock:
@@ -237,6 +252,7 @@ class Database:
 
     def count(self, table: str) -> int:
         """Count rows in an entity table."""
+        _check_table(table)
         with self._lock:
             row = self._conn.execute(
                 f"SELECT COUNT(*) as cnt FROM [{table}]"
@@ -245,13 +261,15 @@ class Database:
 
     def table_exists_with_data(self, table: str) -> bool:
         """Check if a table exists and has at least one row."""
+        _check_table(table)
         with self._lock:
             try:
                 row = self._conn.execute(
                     f"SELECT COUNT(*) as cnt FROM [{table}]"
                 ).fetchone()
                 return row["cnt"] > 0
-            except sqlite3.OperationalError:
+            except sqlite3.OperationalError as e:
+                logger.debug("Table %s does not exist or is inaccessible: %s", table, e)
                 return False
 
     # -- Settings (key-value) ------------------------------------------------
@@ -266,7 +284,8 @@ class Database:
             return None
         try:
             return json.loads(row["value"])
-        except json.JSONDecodeError:
+        except json.JSONDecodeError as e:
+            logger.warning("Corrupt JSON in setting '%s': %s", key, e)
             return None
 
     def set_setting(self, key: str, value: dict) -> None: