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/src/lib/usePeerPresence.test.ts

@@ -0,0 +1,42 @@
+import { describe, expect, it } from 'vitest';
+
+import {
+  createPeerPresenceChannelName,
+  getEffectivePresenceState,
+  PRESENCE_DEVICE_STALE_MS,
+} from './presence';
+
+describe('getEffectivePresenceState', () => {
+  const now = Date.parse('2026-04-24T12:00:00.000Z');
+
+  it('keeps a live profile state when a device checked in recently', () => {
+    const seenAt = new Date(now - PRESENCE_DEVICE_STALE_MS + 1_000).toISOString();
+
+    expect(getEffectivePresenceState('online', seenAt, now)).toBe('online');
+    expect(getEffectivePresenceState('idle', seenAt, now)).toBe('idle');
+    expect(getEffectivePresenceState('dnd', seenAt, now)).toBe('dnd');
+  });
+
+  it('falls back to offline when the latest device check-in is stale', () => {
+    const seenAt = new Date(now - PRESENCE_DEVICE_STALE_MS - 1_000).toISOString();
+
+    expect(getEffectivePresenceState('online', seenAt, now)).toBe('offline');
+  });
+
+  it('respects explicit offline and invisible states', () => {
+    const seenAt = new Date(now).toISOString();
+
+    expect(getEffectivePresenceState('offline', seenAt, now)).toBe('offline');
+    expect(getEffectivePresenceState('invisible', seenAt, now)).toBe('invisible');
+  });
+});
+
+describe('createPeerPresenceChannelName', () => {
+  it('keeps simultaneous subscriptions for the same user isolated', () => {
+    const userId = '48c2959f-1a21-4de4-a69b-7481a3e68fbd';
+
+    expect(createPeerPresenceChannelName(userId, 'header')).not.toBe(
+      createPeerPresenceChannelName(userId, 'profile-card'),
+    );
+  });
+});