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/MentionAutocomplete.tsx

@@ -14,13 +14,7 @@ interface Props {
 // Dropdown shown above the composer when the user has typed `@` followed
 // by the start of a member name. Keyboard-first — arrow keys move through,
 // enter/tab commits, escape cancels.
-export function MentionAutocomplete({
-  members,
-  query,
-  excludeUserId,
-  onSelect,
-  onClose,
-}: Props) {
+export function MentionAutocomplete({ members, query, excludeUserId, onSelect, onClose }: Props) {
   const q = query.toLowerCase();
   const matches = members
     .filter((m) => m.userId !== excludeUserId)
@@ -67,7 +61,7 @@ export function MentionAutocomplete({
     <div
       role="listbox"
       aria-label="Mitglieder"
-      className="absolute bottom-full left-0 right-0 z-20 mb-2 max-h-64 overflow-y-auto rounded-xl border border-line bg-surface-2 p-1 shadow-xl"
+      className="absolute bottom-full left-0 right-0 z-20 mb-2 max-h-64 overflow-y-auto rounded-xl border border-line bg-surface-2 p-1 shadow-xl dark:bg-[#2b2d31]"
     >
       {matches.map((m, idx) => {
         const name = m.profile?.displayName ?? m.profile?.username ?? '?';
@@ -85,7 +79,9 @@ export function MentionAutocomplete({
             }}
             className={
               'flex w-full cursor-pointer items-center gap-2 rounded-lg px-2 py-1.5 text-left text-sm transition ' +
-              (isActive ? 'bg-accent/20 text-fg' : 'text-fg-muted hover:bg-surface-3')
+              (isActive
+                ? 'bg-accent/20 text-fg'
+                : 'text-fg-muted hover:bg-surface-3 dark:hover:bg-[#383a40]')
             }
           >
             <Avatar