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/window-state.ts

@@ -0,0 +1,91 @@
+// Persists BrowserWindow bounds + maximized state to userData/<filename>.
+// Saves are debounced 500ms on move/resize, and fired synchronously on close.
+// Validates loaded bounds against the current display layout to avoid
+// restoring a window onto a display that no longer exists.
+
+import { app, BrowserWindow, screen } from 'electron';
+import { promises as fs } from 'node:fs';
+import path from 'node:path';
+
+interface State {
+  x?: number;
+  y?: number;
+  width: number;
+  height: number;
+  maximized?: boolean;
+}
+
+const DEFAULT: State = { width: 1200, height: 800 };
+
+function isOnAnyDisplay(bounds: { x: number; y: number; width: number; height: number }): boolean {
+  for (const d of screen.getAllDisplays()) {
+    const wa = d.workArea;
+    if (
+      bounds.x >= wa.x &&
+      bounds.y >= wa.y &&
+      bounds.x + bounds.width <= wa.x + wa.width + 8 &&
+      bounds.y + bounds.height <= wa.y + wa.height + 8
+    ) {
+      return true;
+    }
+  }
+  return false;
+}
+
+export async function loadState(filename: string): Promise<State> {
+  const filePath = path.join(app.getPath('userData'), filename);
+  try {
+    const raw = await fs.readFile(filePath, 'utf8');
+    const parsed = JSON.parse(raw) as Partial<State>;
+    const width = typeof parsed.width === 'number' ? parsed.width : DEFAULT.width;
+    const height = typeof parsed.height === 'number' ? parsed.height : DEFAULT.height;
+    const state: State = { width, height };
+    if (typeof parsed.x === 'number' && typeof parsed.y === 'number') {
+      if (isOnAnyDisplay({ x: parsed.x, y: parsed.y, width, height })) {
+        state.x = parsed.x;
+        state.y = parsed.y;
+      }
+    }
+    if (parsed.maximized) state.maximized = true;
+    return state;
+  } catch {
+    return { ...DEFAULT };
+  }
+}
+
+export function attach(win: BrowserWindow, filename: string): void {
+  const filePath = path.join(app.getPath('userData'), filename);
+  let saveTimer: NodeJS.Timeout | null = null;
+
+  const writeNow = (): void => {
+    if (win.isDestroyed()) return;
+    const bounds = win.getNormalBounds();
+    const state: State = {
+      x: bounds.x,
+      y: bounds.y,
+      width: bounds.width,
+      height: bounds.height,
+      maximized: win.isMaximized(),
+    };
+    // Fire-and-forget; exceptions are logged but non-fatal.
+    void fs
+      .writeFile(filePath, JSON.stringify(state), 'utf8')
+      .catch((err: unknown) => {
+        console.warn('[window-state] write failed', err);
+      });
+  };
+
+  const schedule = (): void => {
+    if (saveTimer) clearTimeout(saveTimer);
+    saveTimer = setTimeout(writeNow, 500);
+  };
+
+  win.on('move', schedule);
+  win.on('resize', schedule);
+  win.on('maximize', schedule);
+  win.on('unmaximize', schedule);
+  win.on('close', () => {
+    if (saveTimer) clearTimeout(saveTimer);
+    writeNow();
+  });
+}