feat(desktop): port v0.11.4-v0.15.2 from Tauri to Electron + Discord-parity audio (v0.16.0)

Chronological port of every Tauri release commit (v0.11.4 -> v0.15.2)
into the Electron rebuild, plus Discord-style audio handling that goes
beyond the Tauri original.

Highlights:
  - All 17 Tauri release commits ported (audio fixes, custom notification
    sound, Discord-style chat UX, profile banner, changelog page,
    Discord-parity call UX, screen-share echo + re-watch UX, audio-loop
    fix).
  - Native napi-rs audio-loopback addon with WASAPI process-loopback:
      * EXCLUDE_TARGET_PROCESS_TREE for full-screen shares -> peers
        never hear themselves echoed back through the capture.
      * INCLUDE_TARGET_PROCESS_TREE for window shares -> only the
        picked window's audio is captured, not the whole OS mixer
        (Discord parity).
      * HWND -> PID resolution via Win32 GetWindowThreadProcessId.
  - Discord-style screen-source picker (thumbnail grid, screens vs
    apps tabs, live-refreshing thumbnails).
  - Hash routing fix for packaged builds (file:// can't resolve
    BrowserRouter paths).
  - Tauri sources removed (apps/desktop/src-tauri).

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

apps/desktop/electron/modules/updater.ts

@@ -0,0 +1,84 @@
+// Auto-updater. Wraps electron-updater; configuration (feed URL) lives in
+// package.json's `build.publish`. In dev (`app.isPackaged === false`) we
+// short-circuit everything — the feed server is production-only and
+// hitting it every launch from a dev machine just adds noise.
+
+import { app, BrowserWindow, ipcMain } from 'electron';
+import electronUpdater, {
+  type ProgressInfo,
+  type UpdateInfo as BuilderUpdateInfo,
+} from 'electron-updater';
+
+// electron-updater is a CJS module; named ESM imports don't work. Pull
+// autoUpdater off the default export instead.
+const { autoUpdater } = electronUpdater;
+
+import {
+  CHANNELS,
+  type UpdateCheckResult,
+  type UpdateInfo,
+  type UpdateProgress,
+} from '../ipc-types';
+
+let cached: BuilderUpdateInfo | null = null;
+
+function toPublicInfo(info: BuilderUpdateInfo | null): UpdateInfo | null {
+  if (!info) return null;
+  const notes = info.releaseNotes;
+  let releaseNotes: string | null = null;
+  if (typeof notes === 'string') releaseNotes = notes;
+  else if (Array.isArray(notes)) releaseNotes = notes.map((r) => r.note).join('\n\n');
+  return {
+    version: info.version ?? '',
+    releaseNotes,
+  };
+}
+
+export function register(mainWindow: BrowserWindow): void {
+  autoUpdater.autoDownload = false;
+  autoUpdater.autoInstallOnAppQuit = false;
+
+  autoUpdater.on('download-progress', (p: ProgressInfo) => {
+    if (mainWindow.isDestroyed()) return;
+    const payload: UpdateProgress = {
+      percent: p.percent ?? 0,
+      transferred: p.transferred ?? 0,
+      total: p.total ?? 0,
+    };
+    mainWindow.webContents.send(CHANNELS.UPDATER_EVT_PROGRESS, payload);
+  });
+
+  ipcMain.handle(CHANNELS.UPDATER_CHECK, async (): Promise<UpdateCheckResult> => {
+    if (!app.isPackaged) {
+      return { available: false, info: null };
+    }
+    try {
+      const result = await autoUpdater.checkForUpdates();
+      if (!result || !result.updateInfo) {
+        cached = null;
+        return { available: false, info: null };
+      }
+      const current = app.getVersion();
+      const remote = result.updateInfo.version;
+      if (!remote || remote === current) {
+        cached = null;
+        return { available: false, info: null };
+      }
+      cached = result.updateInfo;
+      return { available: true, info: toPublicInfo(cached) };
+    } catch (err: unknown) {
+      const msg = err instanceof Error ? err.message : String(err);
+      if (!/ENOTFOUND|ETIMEDOUT|ECONNRESET|404/i.test(msg)) {
+        console.warn('[updater] check failed', err);
+      }
+      return { available: false, info: null };
+    }
+  });
+
+  ipcMain.handle(CHANNELS.UPDATER_DOWNLOAD_INSTALL, async (): Promise<void> => {
+    if (!app.isPackaged) return;
+    if (!cached) throw new Error('no pending update — call check first');
+    await autoUpdater.downloadUpdate();
+    autoUpdater.quitAndInstall();
+  });
+}