feat(clients): scaffold mobile (Capacitor) + desktop (Electron) shells

Plan + decisions in CLIENTS.md (parallel mobile+desktop; desktop = technician
client + existing remote-control agent host; mobile = Capacitor wrap).

- desktop/: Electron technician client — loads the live Connect UI, native
  screen capture via setDisplayMediaRequestHandler, persisted session, external
  links to browser; electron-builder config for Win/Mac/Linux installers.
- mobile/: Capacitor project — server.url loads Connect UI, push/camera/status-bar
  plugins declared, www splash fallback; iOS/Android added via `cap add`.
- Reuses the existing /api/v1 + Bearer auth backend; no web-code changes.
- .gitignore: ignore generated mobile/android, mobile/ios platform dirs.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

desktop/README.md

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+# Biz Connect — Desktop client
+
+Electron shell that loads the live Connect web UI and adds native screen capture. See the
+overall plan in [../CLIENTS.md](../CLIENTS.md).
+
+## Run (dev)
+```bash
+npm install
+SERVER_URL=http://localhost:8090 npm start     # default is https://remote.bizgaze.com
+```
+
+## Build installers
+```bash
+npm run dist        # electron-builder → Win NSIS / Mac dmg / Linux AppImage
+```
+Signed, trusted installers need certificates:
+- **Windows:** an EV (or OV) code-signing certificate.
+- **macOS:** Apple Developer ID cert + notarization (`CSC_LINK`, `APPLE_ID`, `APPLE_APP_SPECIFIC_PASSWORD`).
+
+## Notes
+- The window loads `${SERVER_URL}/home`; relative `/api` and `/ws` URLs work because the
+  origin is the server itself — no web-code changes.
+- `setDisplayMediaRequestHandler` in `main.js` is what makes "Share Screen" work in Electron;
+  it currently defaults to the primary display. Swap in a source-picker for production.
+- The session is persisted (`persist:bizconnect`) so login survives restarts.
+- `window.__NATIVE__ === 'desktop'` is exposed for the web UI to feature-detect.

desktop/main.js

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+// Biz Connect — technician desktop client (Electron main process).
+//
+// This is a thin shell: it loads the live Connect web UI from the server origin, so every
+// relative /api and /ws URL in the web app keeps working unchanged. What it adds over a
+// browser tab:
+//   - native full-screen capture for "Share Screen" (setDisplayMediaRequestHandler)
+//   - a real desktop window (no browser chrome), persisted login session
+//   - external links open in the user's browser, not inside the app
+//
+// Server origin is configurable so the same build works against prod or a dev server.
+const { app, BrowserWindow, session, desktopCapturer, shell, Menu } = require('electron');
+const path = require('path');
+
+const SERVER_URL = (process.env.SERVER_URL || 'https://remote.bizgaze.com').replace(/\/+$/, '');
+
+let win;
+
+function createWindow() {
+  win = new BrowserWindow({
+    width: 1200,
+    height: 800,
+    minWidth: 880,
+    minHeight: 600,
+    title: 'Biz Connect',
+    backgroundColor: '#0f1830',
+    webPreferences: {
+      preload: path.join(__dirname, 'preload.js'),
+      contextIsolation: true,
+      nodeIntegration: false,
+      // Persist cookies/localStorage so the technician stays logged in between launches.
+      partition: 'persist:bizconnect',
+    },
+  });
+
+  win.loadURL(SERVER_URL + '/home');
+
+  // Open target=_blank / external links in the system browser instead of a new Electron window.
+  win.webContents.setWindowOpenHandler(({ url }) => {
+    if (!url.startsWith(SERVER_URL)) { shell.openExternal(url); return { action: 'deny' }; }
+    return { action: 'allow' };
+  });
+}
+
+// Electron requires an explicit handler for getDisplayMedia(); without it the web UI's
+// "Share Screen" silently fails. Default to the primary display with loopback audio.
+// A production build can swap this for a source-picker window.
+function registerDisplayMediaHandler() {
+  session.fromPartition('persist:bizconnect').setDisplayMediaRequestHandler((request, callback) => {
+    desktopCapturer.getSources({ types: ['screen', 'window'] }).then((sources) => {
+      callback(sources.length ? { video: sources[0], audio: 'loopback' } : {});
+    }).catch(() => callback({}));
+  });
+}
+
+app.whenReady().then(() => {
+  registerDisplayMediaHandler();
+  createWindow();
+  Menu.setApplicationMenu(null); // hide the default menu bar; the web UI is the chrome
+  app.on('activate', () => { if (BrowserWindow.getAllWindows().length === 0) createWindow(); });
+});
+
+app.on('window-all-closed', () => { if (process.platform !== 'darwin') app.quit(); });

desktop/package.json

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+{
+  "name": "biz-connect-desktop",
+  "version": "0.1.0",
+  "description": "Biz Connect technician desktop client — loads the Connect web UI with native screen capture",
+  "main": "main.js",
+  "scripts": {
+    "start": "electron .",
+    "dist": "electron-builder"
+  },
+  "devDependencies": {
+    "electron": "^31.0.0",
+    "electron-builder": "^24.13.3"
+  },
+  "build": {
+    "appId": "com.bizgaze.connect.desktop",
+    "productName": "Biz Connect",
+    "files": ["main.js", "preload.js", "assets/**"],
+    "win": { "target": "nsis" },
+    "mac": { "target": "dmg", "category": "public.app-category.business" },
+    "linux": { "target": "AppImage" }
+  }
+}

desktop/preload.js

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+// Minimal, safe bridge into the web UI. Runs with contextIsolation, so it only exposes a
+// frozen marker the web app can feature-detect against (e.g. to hide the PWA install prompt
+// or prefer native push). No Node APIs are exposed to page JS.
+const { contextBridge } = require('electron');
+
+contextBridge.exposeInMainWorld('__NATIVE__', 'desktop');
+contextBridge.exposeInMainWorld('bizConnectNative', Object.freeze({
+  platform: 'desktop',
+  version: process.env.npm_package_version || '0.1.0',
+}));