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/src/alerts/producers/index.ts

@@ -0,0 +1,37 @@
+import type { DatabaseSync } from 'node:sqlite';
+import type { Alert } from '../AlertEngine.ts';
+import type { AlertProducer, ProducerFrequency } from './types.ts';
+
+export type { AlertProducer, ProducerFrequency } from './types.ts';
+
+const producers: AlertProducer[] = [];
+
+/** Register a producer (called once at startup). */
+export function registerProducer(p: AlertProducer): void {
+  producers.push(p);
+}
+
+/** Run all producers for a given frequency tier. */
+export async function runProducers(
+  db: DatabaseSync,
+  frequency: ProducerFrequency,
+): Promise<Alert[]> {
+  const results: Alert[] = [];
+  const tier = producers.filter((p) => p.frequency === frequency);
+
+  for (const producer of tier) {
+    try {
+      const alerts = await producer.check(db);
+      results.push(...alerts);
+    } catch (err) {
+      console.error(`[alert:${producer.alertType}] check failed:`, err);
+    }
+  }
+
+  return results;
+}
+
+/** Get all registered producer types. */
+export function registeredAlertTypes(): string[] {
+  return producers.map((p) => p.alertType);
+}