feat: v0.5.0 header, switcher, phone key bar, shared polling, Matrix "needs you"

- Header: no SSO chip ("Sign in again" only on expiry), state dot on the
  session chip, LIVE as a dot, ⋯ menu for text size/notifications/fullscreen,
  Panels badge for waiting sessions and alerts.
- Session switcher on the chip; bare URL reattaches the last session; + New
  opens the panel form with project folders.
- Notifications when other sessions start waiting; alerts polled with the
  panels closed; one tab polls for all tabs over BroadcastChannel.
- Sidebar: context bar per session instead of the Context panel; compact
  Repo/CI with "Ask Claude to fix CI"; legible labels.
- Phone: key bar, drawer with backdrop, visualViewport-aware layout, DOM
  renderer on touch, compact connection dot.
- devdesk-notify-matrix: one Matrix message per wait that lasts
  DEVDESK_MATRIX_DELAY seconds with nobody attached.

Closes #8
Closes #13
Closes #14
Closes #15
Closes #16
Closes #17
Closes #28

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

web/src/connection.js

@@ -12,11 +12,17 @@ export async function fetchToken() {
   const res = await fetch(tokenUrl(window.location), {
     cache: 'no-store', credentials: 'same-origin', redirect: 'manual',
   });
-  if (res.type === 'opaqueredirect') throw new AuthExpiredError('SSO session expired');
+  if (res.type === 'opaqueredirect') {
+    // Any request can discover an expired Authelia session; the header shows
+    // "Sign in again" when this fires (devdesk#13).
+    window.dispatchEvent(new CustomEvent('devdesk:auth', { detail: 'expired' }));
+    throw new AuthExpiredError('SSO session expired');
+  }
   if (res.status === 401 || res.status === 403 || res.status === 407) {
     throw new UnauthorizedError(`HTTP ${res.status}`);
   }
   if (!res.ok) throw new Error(`token request failed: HTTP ${res.status}`);
+  window.dispatchEvent(new CustomEvent('devdesk:auth', { detail: 'ok' }));
   const body = await res.json();
   return body.token || '';
 }