Tag plugin logs structurally and surface the active plugin in System Logs (#418)

- get_logger() now returns a PluginLoggerAdapter when given a plugin_id,
  so every plugin log call is stamped with plugin_id automatically instead
  of only calls that explicitly passed extra={'plugin_id': ...}. This makes
  the "[Plugin: x]" prefix reliable in the journalctl-backed log stream.
- display_controller publishes the currently active mode/plugin to the
  shared cache whenever it changes, exposed via a new
  GET /api/v3/display/current-status endpoint.
- System Logs page: adds a "Now showing" banner backed by that endpoint, a
  plugin filter dropdown (populated from parsed log lines), a plugin badge
  per log entry, and fixes log parsing to handle the short-iso timestamp
  format journalctl actually returns (the old regex only matched syslog
  timestamps, so level/plugin extraction silently never ran).

Co-authored-by: Claude <noreply@anthropic.com>

src/plugin_system/base_plugin.py

@@ -86,7 +86,9 @@ class BasePlugin(ABC):
         self.display_manager: Any = display_manager
         self.cache_manager: Any = cache_manager
         self.plugin_manager: Any = plugin_manager
-        self.logger: logging.Logger = get_logger(f"plugin.{plugin_id}", plugin_id=plugin_id)
+        # get_logger returns a PluginLoggerAdapter here (plugin_id given), which
+        # stamps every record with plugin_id so it survives into formatted output.
+        self.logger = get_logger(f"plugin.{plugin_id}", plugin_id=plugin_id)
         self.enabled: bool = config.get("enabled", True)
 
         self.logger.info("Initialized plugin: %s", plugin_id)