Initial CloudLink scaffold: E2E encrypted PWA with messaging and cloud drive

- Zero-knowledge architecture: all encryption/decryption client-side via Web Crypto API
- AES-GCM 256 for messages, files, and key wrapping; PBKDF2 for password-based key derivation
- Node.js/TypeScript backend: JWT auth with refresh rotation, argon2id passwords, TOTP 2FA
- PostgreSQL schema: encrypted blobs only, server never stores plaintext
- Real-time messaging via WebSocket relay (server routes ciphertext, cannot read it)
- Encrypted file upload/download with per-file keys wrapped by user master key
- React PWA frontend: Vite + Tailwind + service worker for offline support
- Docker Compose: postgres + backend + frontend + nginx with TLS

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

nginx/nginx.conf

@@ -0,0 +1,57 @@
+events { worker_connections 1024; }
+
+http {
+    include mime.types;
+    default_type application/octet-stream;
+    sendfile on;
+    keepalive_timeout 65;
+    client_max_body_size 110m;
+
+    # Redirect HTTP → HTTPS
+    server {
+        listen 80;
+        return 301 https://$host$request_uri;
+    }
+
+    server {
+        listen 443 ssl http2;
+        ssl_certificate     /etc/nginx/ssl/fullchain.pem;
+        ssl_certificate_key /etc/nginx/ssl/privkey.pem;
+        ssl_protocols TLSv1.2 TLSv1.3;
+        ssl_ciphers HIGH:!aNULL:!MD5;
+        ssl_session_cache shared:SSL:10m;
+
+        # Security headers
+        add_header Strict-Transport-Security "max-age=31536000; includeSubDomains" always;
+        add_header X-Frame-Options DENY always;
+        add_header X-Content-Type-Options nosniff always;
+        add_header Referrer-Policy no-referrer always;
+        add_header Content-Security-Policy "default-src 'self'; script-src 'self' 'unsafe-inline'; style-src 'self' 'unsafe-inline'; connect-src 'self' wss:;" always;
+
+        # API
+        location /api/ {
+            proxy_pass http://backend:3001/api/;
+            proxy_http_version 1.1;
+            proxy_set_header Host $host;
+            proxy_set_header X-Real-IP $remote_addr;
+            proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
+            proxy_set_header X-Forwarded-Proto $scheme;
+        }
+
+        # WebSocket
+        location /ws {
+            proxy_pass http://backend:3001/ws;
+            proxy_http_version 1.1;
+            proxy_set_header Upgrade $http_upgrade;
+            proxy_set_header Connection "Upgrade";
+            proxy_set_header Host $host;
+            proxy_read_timeout 86400;
+        }
+
+        # Frontend (SPA)
+        location / {
+            proxy_pass http://frontend:80/;
+            proxy_set_header Host $host;
+        }
+    }
+}