feat: major cleanup + death alerts + idle detection + Discord webhooks

Cleanup:
- Removed 109 stale asset files from static/assets/ (was 122, now 13)
- Removed static/v2/ entirely (was duplicate of root assets)
- Removed dead dashboard code: DashboardView, Layout, GlobalStats,
  CharacterCard, CharacterGrid, VitalBar, TabContainer, CombatTab,
  RaresTab, MapTab, InventoryTab, global.css, MapTransformContext
- Removed recharts dependency (425KB chunk eliminated)
- CSS reduced from 17KB to 10KB
- Added deploy-frontend.sh script for one-command build+deploy
- Updated CLAUDE.md with combat_stats, share_*, dungeon_map events
  and React frontend architecture

Death alerts (frontend + backend):
- Frontend: DeathNotification component with red banner + sawtooth
  sound when vitae goes from 0 to >0
- Backend: detects vitae transition in vitals handler, sends Discord
  webhook to #aclog with "☠️ CHARACTER died! (vitae: X%)"
- Rate-limited: max 1 Discord alert per character per 5 minutes

Idle detection (backend):
- Background task runs every 60 seconds
- Detects: vt_state "default"/"idle" OR kph=0 while in combat/hunt
- Sends Discord webhook: "⚠️ CHARACTER appears idle (state: X, KPH: 0)"
- Auto-clears alert when character becomes active again
- No duplicate alerts for same idle period

Discord integration:
- DISCORD_ACLOG_WEBHOOK env var for webhook URL
- Used by both death alerts and idle detection
- Graceful fallback when not configured

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

frontend/vite.config.ts

@@ -5,7 +5,7 @@ export default defineConfig({
   plugins: [react()],
   base: '/',
   build: {
-    outDir: '../static/v2',  // still build to v2/ first, then we copy
+    outDir: '../static/_build',  // temp dir, deploy script copies to static/
     emptyOutDir: true,
     chunkSizeWarningLimit: 300,
     rollupOptions: {