Enhance: Implement exhaustive background caching and recursive data loading

- Implemented aggressive room-wide background caching engine in LauncherBackgroundSync.svelte.
- Added inc_file_li and inc_all_file_li support to Event and Event Location object loaders for total room coverage.
- Switched to proven V1 download path (/hosted_file/) to resolve V3 CRUD binary delivery issues.
- Optimized Electron bridge with download locking and flat-hash storage matching legacy 'perfect' logic.
- Standardized all Electron IPC methods and parameters to snake_case.
- Added visual sync progress indicator for room caching status.

src/routes/events/[event_id]/+layout.ts

@@ -46,7 +46,7 @@ export async function load({ params, parent, url }) {
         const load_event_obj: ae_Event | null = await events_func.load_ae_obj_id__event({
             api_cfg: ae_acct.api,
             event_id: event_id,
-            // inc_file_li: true,
+            inc_file_li: true,
             // inc_device_li: true,
             inc_location_li: true,
             inc_session_li: true,