Fix: Standardize Electron bridge and implement robust caching

- Refactored all IPC methods and parameters to snake_case for consistency with SvelteKit.
- Implemented exhaustive background caching engine with download locking.
- Reverted to legacy-proven flat hash storage pattern (hash.file).
- Added axios for reliable stream-based binary downloads.
- Updated preload and main handlers to support recursive room data fetching.

src/main/shell_handlers.ts

@@ -0,0 +1,38 @@
+import { ipcMain, shell } from 'electron';
+import { exec } from 'child_process';
+import * as path from 'path';
+import * as fs from 'fs';
+
+export function registerShellHandlers() {
+  // Open a local directory in the OS File Manager
+  ipcMain.handle('native:open-folder', async (event, folderPath: string) => {
+    console.log(`Native: Opening folder ${folderPath}`);
+    const error = await shell.openPath(folderPath);
+    return { success: !error, error };
+  });
+
+  // Run a generic shell command (Whitelisted logic can be added here)
+  ipcMain.handle('native:run-cmd', async (event, command: string) => {
+    console.log(`Native: Running command: ${command}`);
+    return new Promise((resolve) => {
+      exec(command, (error, stdout, stderr) => {
+        resolve({
+          success: !error,
+          stdout,
+          stderr,
+          error: error ? error.message : null
+        });
+      });
+    });
+  });
+
+  // Specific handler for launching a presentation file
+  ipcMain.handle('native:launch-file', async (event, filePath: string) => {
+    console.log(`Native: Launching file: ${filePath}`);
+    if (!fs.existsSync(filePath)) {
+      return { success: false, error: 'File not found' };
+    }
+    const error = await shell.openPath(filePath);
+    return { success: !error, error };
+  });
+}