Add callback management API/UI and theme support

- Add callback CRUD endpoints (create, update, delete, list)
- Add callback management UI with all 11 callback events support
- Add light/dark theme switcher with localStorage persistence
- Improve button styling (wider buttons, simplified text)
- Extend ConfigManager with callback operations

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

media_server/config_manager.py

@@ -8,7 +8,7 @@ from typing import Optional
 
 import yaml
 
-from .config import ScriptConfig, settings
+from .config import CallbackConfig, ScriptConfig, settings
 
 logger = logging.getLogger(__name__)
 
@@ -171,6 +171,114 @@ class ConfigManager:
 
             logger.info(f"Script '{name}' deleted from config")
 
+    def add_callback(self, name: str, config: CallbackConfig) -> None:
+        """Add a new callback to config.
+
+        Args:
+            name: Callback name (must be unique).
+            config: Callback configuration.
+
+        Raises:
+            ValueError: If callback already exists.
+            IOError: If config file cannot be written.
+        """
+        with self._lock:
+            # Read YAML
+            if not self._config_path.exists():
+                data = {}
+            else:
+                with open(self._config_path, "r", encoding="utf-8") as f:
+                    data = yaml.safe_load(f) or {}
+
+            # Check if callback already exists
+            if "callbacks" in data and name in data["callbacks"]:
+                raise ValueError(f"Callback '{name}' already exists")
+
+            # Add callback
+            if "callbacks" not in data:
+                data["callbacks"] = {}
+            data["callbacks"][name] = config.model_dump(exclude_none=True)
+
+            # Write YAML
+            self._config_path.parent.mkdir(parents=True, exist_ok=True)
+            with open(self._config_path, "w", encoding="utf-8") as f:
+                yaml.dump(data, f, default_flow_style=False, sort_keys=False)
+
+            # Update in-memory settings
+            settings.callbacks[name] = config
+
+            logger.info(f"Callback '{name}' added to config")
+
+    def update_callback(self, name: str, config: CallbackConfig) -> None:
+        """Update an existing callback.
+
+        Args:
+            name: Callback name.
+            config: New callback configuration.
+
+        Raises:
+            ValueError: If callback does not exist.
+            IOError: If config file cannot be written.
+        """
+        with self._lock:
+            # Read YAML
+            if not self._config_path.exists():
+                raise ValueError(f"Config file not found: {self._config_path}")
+
+            with open(self._config_path, "r", encoding="utf-8") as f:
+                data = yaml.safe_load(f) or {}
+
+            # Check if callback exists
+            if "callbacks" not in data or name not in data["callbacks"]:
+                raise ValueError(f"Callback '{name}' does not exist")
+
+            # Update callback
+            data["callbacks"][name] = config.model_dump(exclude_none=True)
+
+            # Write YAML
+            with open(self._config_path, "w", encoding="utf-8") as f:
+                yaml.dump(data, f, default_flow_style=False, sort_keys=False)
+
+            # Update in-memory settings
+            settings.callbacks[name] = config
+
+            logger.info(f"Callback '{name}' updated in config")
+
+    def delete_callback(self, name: str) -> None:
+        """Delete a callback from config.
+
+        Args:
+            name: Callback name.
+
+        Raises:
+            ValueError: If callback does not exist.
+            IOError: If config file cannot be written.
+        """
+        with self._lock:
+            # Read YAML
+            if not self._config_path.exists():
+                raise ValueError(f"Config file not found: {self._config_path}")
+
+            with open(self._config_path, "r", encoding="utf-8") as f:
+                data = yaml.safe_load(f) or {}
+
+            # Check if callback exists
+            if "callbacks" not in data or name not in data["callbacks"]:
+                raise ValueError(f"Callback '{name}' does not exist")
+
+            # Delete callback
+            del data["callbacks"][name]
+
+            # Write YAML
+            with open(self._config_path, "w", encoding="utf-8") as f:
+                yaml.dump(data, f, default_flow_style=False, sort_keys=False)
+
+            # Update in-memory settings
+            if name in settings.callbacks:
+                del settings.callbacks[name]
+
+            logger.info(f"Callback '{name}' deleted from config")
+
 
 # Global config manager instance
 config_manager = ConfigManager()