feat(launcher): implement device heartbeat and background sync engine

- Hardened 'find_object_id' in Dexie to support 'event_' prefixed IDs.
- Implemented singleton 'LauncherBackgroundSync' in root launcher layout.
- Added V3-compliant heartbeat and room refresh cycles.
- Fixed redundant component imports and Skeleton UI prop errors.
- Added 'inc_file_li' support to event API loader.

src/lib/app_components/e_app_codemirror_v5.svelte

@@ -43,7 +43,7 @@
         class: classes = ''
     }: Props = $props();
 
-    let editor_element: HTMLDivElement = $state();
+    let editor_element: HTMLDivElement | undefined = $state();
     // let editorView: any = $state(); // Removed redundant declaration
     let cm_modules: any = $state(); // To hold the dynamically loaded CodeMirror modules
     let editor_extensions: any[] = $state([]);