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/components/CallControls.tsx

@@ -1,6 +1,7 @@
 import { useTranslation } from 'react-i18next';
 
 import {
+  CaptionsIcon,
   HeadphonesIcon,
   HeadphonesOffIcon,
   MicIcon,
@@ -31,6 +32,10 @@ interface Props {
   /** Toggle the in-call soundboard popover. Active = panel currently open. */
   onToggleSoundboard?: () => void;
   soundboardOpen?: boolean;
+  /** Discord-style live-captions toggle. Optional — pages that don't support
+   *  SpeechRecognition (Firefox) skip the prop and the button is hidden. */
+  onToggleCaptions?: () => void;
+  captionsOn?: boolean;
   participantsOpen?: boolean;
   /** Compact variant used inside the docked call (36px buttons). */
   compact?: boolean;
@@ -54,6 +59,8 @@ export function CallControls({
   onOpenParticipants,
   onToggleSoundboard,
   soundboardOpen = false,
+  onToggleCaptions,
+  captionsOn = false,
   participantsOpen = false,
   compact = false,
   glass = false,
@@ -141,6 +148,22 @@ export function CallControls({
           <MusicIcon className="h-5 w-5" />
         </CallButton>
       )}
+      {onToggleCaptions && (
+        <CallButton
+          label={
+            captionsOn
+              ? t('app:call.captions_off', { defaultValue: 'Untertitel aus' })
+              : t('app:call.captions_on', { defaultValue: 'Untertitel an' })
+          }
+          active={captionsOn}
+          activeTone="accent"
+          onClick={onToggleCaptions}
+          glass={glass}
+          className={btnSize}
+        >
+          <CaptionsIcon className="h-5 w-5" />
+        </CallButton>
+      )}
       {onOpenParticipants && (
         <CallButton
           label={t('app:call.participants', { defaultValue: 'Teilnehmer' })}