feat(FN-1072): add Electron desktop renderer integration

- Add Electron main-process IPC handlers and preload bridges for API proxying, window controls, update install, and platform lookup
- Introduce a desktop renderer entrypoint with DesktopWrapper and a custom frameless TitleBar component
- Add Electron-aware renderer utilities including API transport selection and hooks for runtime detection, auto-update events, and deep links
- Update dashboard header behavior for Electron mode and expand desktop tests across preload, transport, hooks, and title bar flows
- Document the desktop renderer architecture and update desktop package config/dependencies

packages/desktop/src/preload.ts

@@ -1,4 +1,5 @@
 import { contextBridge, ipcRenderer } from "electron";
+import type { ElectronAPI, ElectronApiResponsePayload, WindowControlAction } from "./renderer/types";
 
 export interface FusionDesktopAPI {
   getAppVersion(): Promise<string>;
@@ -6,7 +7,7 @@ export interface FusionDesktopAPI {
   onDashboardReady(callback: () => void): () => void;
 }
 
-const api: FusionDesktopAPI = {
+const fusionDesktop: FusionDesktopAPI = {
   getAppVersion(): Promise<string> {
     return ipcRenderer.invoke("app:get-version");
   },
@@ -22,4 +23,44 @@ const api: FusionDesktopAPI = {
   },
 };
 
-contextBridge.exposeInMainWorld("fusionDesktop", api);
+const electronAPI: ElectronAPI = {
+  invoke(channel: string, payload?: unknown): Promise<unknown> {
+    return ipcRenderer.invoke(channel, payload);
+  },
+  apiRequest(method: string, path: string, body?: unknown): Promise<ElectronApiResponsePayload> {
+    return ipcRenderer.invoke("api-request", { method, path, body });
+  },
+  getServerPort(): Promise<number> {
+    return ipcRenderer.invoke("server:get-port");
+  },
+  windowControl(action: WindowControlAction): Promise<boolean | void> {
+    return ipcRenderer.invoke("window:control", action);
+  },
+  onUpdateAvailable(callback: (info: Record<string, unknown>) => void): () => void {
+    const listener = (_event: unknown, info: Record<string, unknown>) => {
+      callback(info);
+    };
+    ipcRenderer.on("update:available", listener);
+    return () => {
+      ipcRenderer.removeListener("update:available", listener);
+    };
+  },
+  installUpdate(): Promise<void> {
+    return ipcRenderer.invoke("update:install");
+  },
+  onDeepLink(callback: (url: string) => void): () => void {
+    const listener = (_event: unknown, url: string) => {
+      callback(url);
+    };
+    ipcRenderer.on("deep-link", listener);
+    return () => {
+      ipcRenderer.removeListener("deep-link", listener);
+    };
+  },
+  getPlatform() {
+    return ipcRenderer.invoke("system:get-platform");
+  },
+};
+
+contextBridge.exposeInMainWorld("fusionDesktop", fusionDesktop);
+contextBridge.exposeInMainWorld("electronAPI", electronAPI);