feat: Sprint 5 — AI insights, webhooks/Slack, PWA, performance monitoring

AI-Powered Insights (G9):
- Rule-based anomaly detection: budget burn rate, staffing gaps, utilization,
  timeline overruns across all active projects
- AI narrative generation via existing Azure OpenAI integration
- Cached in project dynamicFields to avoid regeneration
- New /analytics/insights page with anomaly feed + project summaries
- Sidebar nav: "AI Insights" under Analytics

Webhook System + Slack (G10):
- Webhook model in Prisma (url, secret, events, isActive)
- HMAC-SHA256 signed payloads with 5s timeout fire-and-forget dispatch
- Slack-aware: routes hooks.slack.com URLs through Slack formatter
- 6 events integrated: allocation.created/updated/deleted, project.created/
  status_changed, vacation.approved
- Admin UI: /admin/webhooks with CRUD, test button, event checkboxes
- webhook router: list, getById, create, update, delete, test

PWA Support (G11):
- manifest.json with standalone display, brand-colored icons (192+512px)
- Service worker: cache-first for static, network-first for API, offline fallback
- ServiceWorkerRegistration component with 60-min update checks
- InstallPrompt banner with 30-day dismissal memory
- Apple Web App meta tags + viewport theme color

Performance Monitoring (A15):
- Pino structured logging (JSON prod, pretty dev) via LOG_LEVEL env
- tRPC logging middleware on all protectedProcedure calls
- Request ID (UUID) per call for log correlation
- Slow query warnings (>500ms) at warn level
- GET /api/perf endpoint: memory, uptime, SSE connections, node version

Fix: renamed scenario.apply to scenario.applyScenario (tRPC reserved word)

Co-Authored-By: claude-flow <ruv@ruv.net>

packages/db/prisma/schema.prisma

@@ -1523,3 +1523,18 @@ model AuditLog {
   @@index([createdAt])
   @@map("audit_logs")
 }
+
+// ─── Webhook ──────────────────────────────────────────────────────────────────
+
+model Webhook {
+  id        String   @id @default(cuid())
+  name      String
+  url       String
+  secret    String?  // HMAC signing secret
+  events    String[] // ["allocation.created", "project.status_changed", etc.]
+  isActive  Boolean  @default(true)
+  createdAt DateTime @default(now())
+  updatedAt DateTime @updatedAt
+
+  @@map("webhooks")
+}