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>

libexec/devdesk-state-hook

@@ -6,6 +6,8 @@
 #   Stop, SessionStart            -> idle
 #   SessionEnd                    -> exited
 # Fires on every tool call, so it stays tiny and only writes when the state changes.
+# Entering "waiting" also starts devdesk-notify-matrix, which posts to Matrix if
+# the wait lasts and nobody is attached (devdesk#28).
 
 input=$(cat)
 
@@ -29,12 +31,26 @@ file="$dir/$session.json"
 if [ "$state" != waiting ] && [ -f "$file" ] && grep -q "\"state\":\"$state\"" "$file"; then
     exit 0
 fi
+# A second Notification during the same wait updates the message but keeps
+# `since`, so the wait stays one wait (one Matrix message at most).
+since=$(date +%s)
+was_waiting=0
+if [ "$state" = waiting ] && grep -q '"state":"waiting"' "$file" 2>/dev/null; then
+    was_waiting=1
+    since=$(jq -rM '.since // empty' "$file" 2>/dev/null) || since=$(date +%s)
+    [[ $since =~ ^[0-9]+$ ]] || since=$(date +%s)
+fi
 mkdir -p "$dir" 2>/dev/null || exit 0
 tmp=$(mktemp "$dir/.$session.XXXXXX" 2>/dev/null) || exit 0
-if jq -cMn --arg s "$state" --arg m "$message" --arg e "$event" \
-    '{state: $s, since: (now | floor), event: $e, message: (if $m == "" then null else $m end)}' >"$tmp"; then
+if jq -cMn --arg s "$state" --arg m "$message" --arg e "$event" --argjson t "$since" \
+    '{state: $s, since: $t, event: $e, message: (if $m == "" then null else $m end)}' >"$tmp"; then
     mv -f "$tmp" "$file"
 else
     rm -f "$tmp"
+    exit 0
+fi
+if [ "$state" = waiting ] && [ "$was_waiting" = 0 ]; then
+    setsid -f "${DEVDESK_LIBEXEC:-/usr/lib/devdesk}/devdesk-notify-matrix" "$session" "$since" \
+        </dev/null >/dev/null 2>&1 || true
 fi
 exit 0