feat(voice): tool endpoints, timer widget, clean Siri-style overlay

Adds the infrastructure for Claude tool use + visual timer.

Tablet API surface (all bearer-authed with VOICE_API_KEY, middleware bypassed):
- /api/voice/tools/weather    — current + short forecast via Open-Meteo
- /api/voice/tools/transport  — tram arrivals by direction / route filter
- /api/voice/tools/events     — Google Calendar today/week
- /api/voice/tools/notes      — notes + shopping lists
- /api/voice/timer            — start (with seconds+label), cancel; GET list (cookie ok)
  Active timers persisted at /data/tablet-timers.json

UI:
- VoiceOverlay stripped to minimal Siri look: no agent emoji/name, just the
  pulsing orb (3-layer radial gradient, independent breath animations),
  subtle status label on wake only, transcription/response text centered.
  Agents distinguished by orb color (Cosmo indigo/violet, Люся pink).
- TimerWidget: bottom-right chip stack with countdown, progress bar, turns
  amber in last 10s. On expiry, fires fullscreen alarm overlay with beep
  (WebAudio osc) + Остановить button.

Other:
- lib/timers.ts — persistent timer store in /data
- lib/voice-tools.ts — shared bearer-auth helper
- middleware — bypass list now covers /api/voice/tools/* and /api/voice/timer

app/page.tsx

@@ -12,6 +12,7 @@ import NotesTab from '@/components/NotesTab'
 import TransportWidget from '@/components/TransportWidget'
 import WeatherAnimation from '@/components/WeatherAnimation'
 import VoiceOverlay from '@/components/VoiceOverlay'
+import TimerWidget from '@/components/TimerWidget'
 
 type Tab = 'home' | 'devices' | 'calendar' | 'notes' | 'settings'
 
@@ -1109,6 +1110,7 @@ function HomePageInner() {
       </AnimatePresence>
 
       <VoiceOverlay />
+      <TimerWidget />
 
       <Sidebar active={tab} onChange={setTab} />