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/widgets.js

@@ -1,7 +1,6 @@
-// Sidebar widgets. In v1 only Sessions is live; Repo/CI and Claude Context get
-// data from devdesk-api in v1.1, Ops Alerts in v2. The "Ask Claude" pattern is
-// already wired: any [data-ask-claude] button types its prompt into the current
-// session without pressing Enter, so you can review it before sending.
+// "Ask Claude": any [data-ask-claude] button (Ops Alerts, Repo/CI) types its
+// prompt into the current session without pressing Enter, so you can review it
+// before sending.
 
 export function bindAskClaude(root, send) {
   root.addEventListener('click', (event) => {