feat(desktop-client): give login and main views their own BrowserWindow

Spawn a separate window per mode keyed by a ?window= query param so each surface keeps its size, devtools, and renderer state independently. Logout now persists the cleared session and switches windows before awaiting the runtime release, avoiding a stale main-window flash on the way out.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

apps/desktop-client/src/preload/bridge.ts

@@ -22,6 +22,11 @@ interface DesktopClientIDScope {
   user_id: number;
 }
 
+interface WindowModeRequest {
+  source?: "auth-state" | "login" | "logout";
+  animate?: boolean;
+}
+
 const rendererProxyRequestChannel = "desktop:renderer-devtools-proxy:request";
 const rendererProxyResponseChannel = "desktop:renderer-devtools-proxy:response";
 
@@ -119,8 +124,8 @@ const desktopBridge = {
       ipcRenderer.invoke("desktop:runtime-session-sync", session) as Promise<null>,
     releaseRuntimeSession: (revoke?: boolean) =>
       ipcRenderer.invoke("desktop:runtime-session-release", revoke) as Promise<null>,
-    setWindowMode: (mode: "login" | "main") =>
-      ipcRenderer.invoke("desktop:set-window-mode", mode) as Promise<null>,
+    setWindowMode: (mode: "login" | "main", request?: WindowModeRequest) =>
+      ipcRenderer.invoke("desktop:set-window-mode", mode, request) as Promise<null>,
     onRuntimeInvalidated: (
       listener: (event: { reason: "account-health"; at: number; accountId?: string }) => void,
     ) => {