feat(electron): add main process, preload, store, protocol, and type definitions

- Add ElectronAPI type definitions and runtime contract (isElectron guard)
- Add electron-store with backend connection data model
- Add centralized API base URL utility (api-base.ts)
- Implement app:// custom protocol with API proxy
- Implement preload script with full contextBridge API
- Complete main process: BrowserWindow config, IPC handlers, window controls
- Register app:// scheme as privileged for secure renderer access

dashboard/electron/preload/index.ts

@@ -1,7 +1,56 @@
-/**
- * Preload script for Electron renderer process
- * This script runs in the main process before renderer loads
- * Use contextBridge to safely expose APIs
- * 
- * Wave 2 implementation will expose specific IPC methods here
- */
+import { contextBridge, ipcRenderer } from 'electron'
+
+// Write __RUNTIME__ tag into the isolated world so renderer can detect Electron
+contextBridge.exposeInMainWorld('__RUNTIME__', {
+  kind: 'electron' as const,
+  versions: process.versions as unknown as Record<string, string>,
+  source: 'tag' as const,
+})
+
+// Expose the full ElectronAPI surface to the renderer process
+contextBridge.exposeInMainWorld('electronAPI', {
+  // ── Platform detection ──────────────────────────────────────────────────
+  getPlatform: () => process.platform,
+
+  // ── Window control ──────────────────────────────────────────────────────
+  minimizeWindow: () => ipcRenderer.invoke('electron:minimize-window'),
+  maximizeWindow: () => ipcRenderer.invoke('electron:maximize-window'),
+  closeWindow: () => ipcRenderer.invoke('electron:close-window'),
+  isMaximized: () => ipcRenderer.invoke('electron:is-maximized'),
+
+  // ── Window event listeners ───────────────────────────────────────────────
+  onWindowMaximized: (callback: () => void) => {
+    const listener = () => callback()
+    ipcRenderer.on('electron:window-maximized', listener)
+    return () => ipcRenderer.removeListener('electron:window-maximized', listener)
+  },
+  onWindowUnmaximized: (callback: () => void) => {
+    const listener = () => callback()
+    ipcRenderer.on('electron:window-unmaximized', listener)
+    return () => ipcRenderer.removeListener('electron:window-unmaximized', listener)
+  },
+
+  // ── Backend CRUD ─────────────────────────────────────────────────────────
+  getBackends: () => ipcRenderer.invoke('electron:get-backends'),
+  addBackend: (conn: object) => ipcRenderer.invoke('electron:add-backend', conn),
+  updateBackend: (id: string, patch: object) =>
+    ipcRenderer.invoke('electron:update-backend', id, patch),
+  removeBackend: (id: string) => ipcRenderer.invoke('electron:remove-backend', id),
+  setActiveBackend: (id: string) =>
+    ipcRenderer.invoke('electron:set-active-backend', id),
+  getActiveBackend: () => ipcRenderer.invoke('electron:get-active-backend'),
+  getActiveBackendUrl: () => ipcRenderer.invoke('electron:get-active-url'),
+
+  // ── App state ───────────────────────────────────────────────────────────
+  isFirstLaunch: () => ipcRenderer.invoke('electron:is-first-launch'),
+  markFirstLaunchComplete: () =>
+    ipcRenderer.invoke('electron:mark-first-launch-complete'),
+  getAppVersion: () => ipcRenderer.invoke('electron:get-app-version'),
+
+  // ── Backend event listener ──────────────────────────────────────────────
+  onBackendChanged: (callback: (backend: { id: string; name: string; url: string; isDefault: boolean; lastConnected?: number } | null) => void) => {
+    const listener = (_event: unknown, backend: { id: string; name: string; url: string; isDefault: boolean; lastConnected?: number } | null) => callback(backend)
+    ipcRenderer.on('electron:backend-changed', listener)
+    return () => ipcRenderer.removeListener('electron:backend-changed', listener)
+  },
+})