Phase 5: alert subscriptions UI + multiple watchlists + queue fixes

UI:
- /alerts page: event history with acknowledge, subscription create/manage with toggle
- /admin/smtp: SMTP config form (host, port, auth, test)
- Watchlist sidebar: dropdown selector for multiple watchlists, create/delete
- Sidebar: alerts count badge, SMTP link under admin
- Mobile tab nav: alerts tab added
- Client trpc.ts: all new API methods + types

Backend:
- watchlists.listByWatchlist procedure + listSymbolsByWatchlist repo fn
- yfinance min-interval 1500->2000ms to reduce Edge 429s
- Fixed e.date.slice error in yfinance-adjustments with typeof guard
- Removed defunct BITF from watchlist+queue
- Cleared 83 failed + 12 backoff queue jobs

Docs:
- FUNCTIONAL_DESIGN.md: alerts + multiple watchlists + SMTP documented
- TECH_DESIGN.md: new modules, tRPC procs, routes updated

app/server/package.json

@@ -16,11 +16,13 @@
   },
   "dependencies": {
     "@trpc/server": "^11.0.0",
+    "nodemailer": "^9.0.3",
     "yahoo-finance2": "^3.15.4",
     "zod": "^4.4.3"
   },
   "devDependencies": {
     "@types/node": "^22.0.0",
+    "@types/nodemailer": "^8.0.1",
     "typescript": "^5.0.0"
   }
 }