Additional improvements

• Removed placeholder for DSN setting.
• Settings form now uses #config_target so Drupal 11.2+ can report overrides.
• Cache Pilot statistics split into different tabs/routes.
• Cache Pilot fragmentation bar is now <figure>.
• Removed dashboard template since it is no longer needed.
• In Drupal's "Status Report," the active DSN connection is displayed.
• Updated connection status severity: OK when connection successfully established, WARNING when DSN is explicitly NULL (assuming override), ERROR when connection fails and is not overridden.

assigned to @Niklan

merged