feature: vibrate and hold urgent match-found and admin-call pushes

[lukepolo]

Makes "Match found" and "Admin is calling you" pushes ring (vibrate and stay on screen) and takes the ring down when it expires or is answered on this device.

• sw-push.js: an urgent push gets requireInteraction and vibration; expiresAt closes it on a plain timer outside waitUntil (a ring closed inside it counts as a silent push), clamped to 5–60s and matched on expiresAt so a superseded timer can't close its replacement
• New closeNotifications(tag) and notificationThreadKey(); the ready check closes MatchFound:<id> on every update after accepting, so a push that lands late is still closed
• useCameraTalkback: closes AdminCall:<matchId> once the talkback plays, reports the call as presence focus (clearing stale focus on mount), and only hangs up if this tab connected
• Labels for the match_found and admin_call push toggles; the quiet-hours text says they ring anyway (all locales)

Merge/deploy: pairs with api#443; safe to ship first (the new fields are ignored until the api sends them).

Tests: the silent-push close timing, the 5s floor for a clock running ahead, a superseded timer closing its replacement, a ring landing after accepting, hanging up from a tab that never connected, and stale focus on the camera page all fail without the fix. Based on DEAFCS af80eb4, 0d3fbe8