Add get_available_models function

- Added function to retrieve only available models for frontend/API use

vidai/database.py

@@ -1910,6 +1910,16 @@ def get_all_models() -> List[Dict[str, Any]]:
     return [dict(row) for row in rows]
 
 
+def get_available_models() -> List[Dict[str, Any]]:
+    """Get all available models."""
+    conn = get_db_connection()
+    cursor = conn.cursor()
+    cursor.execute('SELECT * FROM models WHERE available = 1 ORDER BY name')
+    rows = cursor.fetchall()
+    conn.close()
+    return [dict(row) for row in rows]
+
+
 def create_model(name: str, model_type: str, path: str, vram_estimate: int = 0, available: bool = False) -> bool:
     """Create a new model."""
     conn = get_db_connection()