Fix Database.initialize and remove invalid theme param

- Add initialize() method as alias for connect()
- Remove invalid tab_nav_background_fill theme parameter

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

src/storage/database.py

@@ -183,6 +183,10 @@ class Database:
 
         logger.info(f"Database connected: {self.db_path}")
 
+    async def initialize(self) -> None:
+        """Alias for connect() for compatibility."""
+        await self.connect()
+
     async def close(self) -> None:
         """Close database connection."""
         if self._connection:

src/ui/theme.py

@@ -74,9 +74,6 @@ def create_audiocraft_theme() -> gr.themes.Base:
         block_title_text_color="#f1f5f9",
         block_title_text_color_dark="#f1f5f9",
 
-        # Tabs
-        tab_nav_background_fill="#1e293b",
-
         # Sliders
         slider_color="#3b82f6",
         slider_color_dark="#3b82f6",