mobile: show login screen for stock browsers when not authenticated

Add an inline auth gate to mobile.html that checks /api/auth/me on load.
Skipped when ?native=true (the iOS shell handles auth in background).
Includes a vanilla JS login form (no Lit) reusing the existing login styles.

Bump version to 0.1.2.

web/components/mobile-app.js

@@ -1,5 +1,6 @@
 import { LitElement, html, nothing } from 'lit';
 import { t }            from '../lib/i18n.js';
+import { LoginPage }    from './login-page.js';
 import './shared/inbox-page.js';
 import './shared/chat-page.js';
 import './shared/projects-page.js';
@@ -7,6 +8,8 @@ import './shared/settings-page.js';
 import './shared/file-viewer-mobile.js';
 import './shared/tool-detail-mobile.js';
 
+customElements.define('login-page', LoginPage);
+
 // Sections addressable via the URL hash — same routing style as the desktop
 // sidebar (web/components/sidebar.js). The native iOS shell and mobile browsers
 // share this router so the URL always reflects the active section: native menu