feat(pitch-deck): admin UI for investor + financial-model management

Adds /pitch-admin dashboard with real admin accounts (bcrypt) and full
audit attribution for every state-changing action.

Backend:
- pitch_admins + pitch_admin_sessions tables (migration 002)
- pitch_audit_logs.admin_id + target_investor_id columns
- lib/admin-auth.ts: bcryptjs hashing, single-session enforcement,
  jose JWT with 'pitch-admin' audience claim, requireAdmin guard
- logAudit extended to accept admin_id and target_investor_id
- middleware.ts: gates /pitch-admin/* and /api/admin/* on the admin
  cookie (with bearer-secret fallback for CLI compatibility)
- 14 API routes under /api/admin-auth and /api/admin (login, logout,
  me, dashboard, investors[id] CRUD + resend, admins CRUD,
  fm scenarios + assumptions PATCH)
- Existing /api/admin/{invite,investors,revoke,audit-logs} migrated
  to requireAdmin and now log with admin_id + target_investor_id
- scripts/create-admin.ts CLI bootstrap (npm run admin:create)

Frontend:
- /pitch-admin/login + /pitch-admin/(authed) route group
- AdminShell with sidebar nav + StatCard + AuditLogTable components
- Dashboard with KPIs, recent logins, recent activity
- Investors list with search/filter + resend/revoke inline actions
- Investor detail with inline edit + per-investor audit timeline
- Audit log viewer with actor/action/date filters + pagination
- Financial model scenario list + per-scenario assumption editor
  (categorized, inline edit, before/after diff in audit)
- Admins management (add, deactivate, reset password)

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

pitch-deck/app/api/admin-auth/logout/route.ts

@@ -0,0 +1,17 @@
+import { NextRequest, NextResponse } from 'next/server'
+import {
+  getAdminPayloadFromCookie,
+  revokeAdminSession,
+  clearAdminCookie,
+  logAdminAudit,
+} from '@/lib/admin-auth'
+
+export async function POST(request: NextRequest) {
+  const payload = await getAdminPayloadFromCookie()
+  if (payload) {
+    await revokeAdminSession(payload.sessionId)
+    await logAdminAudit(payload.sub, 'admin_logout', {}, request)
+  }
+  await clearAdminCookie()
+  return NextResponse.json({ success: true })
+}