feat: add contacts phase 2, advanced search, vacation responder, Docker & TOTP 2FA

- Contact groups/lists, vCard import/export (RFC 6350), bulk operations
- Advanced search with JMAP filter panel, search chips, cross-mailbox queries
- Vacation responder with JMAP VacationResponse, settings tab, sidebar indicator
- TOTP two-factor authentication support
- Docker multi-stage build with standalone output and docker-compose
- CSP Report-Only headers and security headers via proxy middleware
- Virtual scrolling for large email lists
- Structured server-side logger (text/JSON, configurable level)
- 450+ tests (contacts, vCard, threads, headers, identity, components)
- Playwright E2E framework setup
- Updated README and ROADMAP with all new features

app/api/health/route.ts

@@ -1,5 +1,6 @@
 import { NextResponse } from 'next/server';
 import { NextRequest } from 'next/server';
+import { logger } from '@/lib/logger';
 
 // Health check thresholds
 const MEMORY_WARNING_THRESHOLD = 0.85; // 85% heap usage
@@ -86,6 +87,8 @@ export async function GET(request: NextRequest) {
       }
     }
 
+    logger.info('Health check', { status, detailed });
+
     return NextResponse.json(response, {
       status: httpStatus,
       headers: {
@@ -96,6 +99,7 @@ export async function GET(request: NextRequest) {
     });
 
   } catch (error) {
+    logger.error('Health check failed', { error: error instanceof Error ? error.message : 'Unknown error' });
     return NextResponse.json(
       {
         status: 'unhealthy',