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/tailwind.config.js

@@ -43,14 +43,14 @@ export default {
         brand: {
           50: '#EEF0FF',
           100: '#DDE0FF',
-          200: '#BDC2FF',
-          300: '#9198FF',
-          400: '#6D73FF',
-          500: '#4F46E5',
-          600: '#4338CA',
-          700: '#3730A3',
-          800: '#312E81',
-          900: '#1E1B4B',
+          200: '#C4CAFF',
+          300: '#9EA7FF',
+          400: '#7885FF',
+          500: '#5865F2',
+          600: '#4752C4',
+          700: '#3C45A5',
+          800: '#313889',
+          900: '#232861',
         },
         // Clean-Rail design tokens. RGB-tuple form so alpha modifiers
         // (e.g. bg-surface/50) work under both themes.
@@ -69,6 +69,7 @@ export default {
         'blob-b': 'blob 28s ease-in-out infinite reverse',
         'fade-in': 'fadeIn 400ms ease-out',
         'slide-up': 'slideUp 350ms ease-out',
+        'slide-down': 'slideDown 350ms ease-out',
         'pulse-ring': 'pulseRing 2s ease-out infinite',
         'audio-pulse': 'audioPulse 1.3s ease-out infinite',
         'live-dot': 'liveDotPulse 1.5s ease-in-out infinite',
@@ -90,6 +91,10 @@ export default {
           from: { opacity: '0', transform: 'translateY(8px)' },
           to: { opacity: '1', transform: 'translateY(0)' },
         },
+        slideDown: {
+          from: { opacity: '0', transform: 'translateY(-12px)' },
+          to: { opacity: '1', transform: 'translateY(0)' },
+        },
         pulseRing: {
           '0%': { transform: 'scale(0.85)', opacity: '0.6' },
           '100%': { transform: 'scale(1.25)', opacity: '0' },