feat: natural language query + production hardening

Features:
- Add /api/ask endpoint for plain-language audit log queries
- Regex-based time/entity extraction (no LLM required for parsing)
- LLM-powered narrative summarisation with OpenAI-compatible APIs
- Graceful fallback to structured bullet lists when LLM is unavailable
- Frontend ask panel with markdown rendering and cited events

Production:
- Harden Dockerfile: non-root user, gunicorn+uvicorn workers
- Add docker-compose.prod.yml with internal networks and health checks
- Add nginx reverse proxy with security headers
- MongoDB no longer exposed externally in production

Tests:
- 29 new tests for ask parsing, query building, and endpoint behaviour
- Fix conftest monkeypatch for routes.ask events collection

Bump version to 1.1.0

nginx/nginx.conf

@@ -0,0 +1,94 @@
+user nginx;
+worker_processes auto;
+error_log /var/log/nginx/error.log warn;
+pid /var/run/nginx.pid;
+
+events {
+    worker_connections 1024;
+}
+
+http {
+    include /etc/nginx/mime.types;
+    default_type application/octet-stream;
+
+    log_format main '$remote_addr - $remote_user [$time_local] "$request" '
+                    '$status $body_bytes_sent "$http_referer" '
+                    '"$http_user_agent" "$http_x_forwarded_for"';
+
+    access_log /var/log/nginx/access.log main;
+
+    sendfile on;
+    tcp_nopush on;
+    tcp_nodelay on;
+    keepalive_timeout 65;
+    types_hash_max_size 2048;
+
+    # Gzip compression
+    gzip on;
+    gzip_vary on;
+    gzip_proxied any;
+    gzip_comp_level 6;
+    gzip_types text/plain text/css text/xml application/json application/javascript application/rss+xml application/atom+xml image/svg+xml;
+
+    # Security headers
+    add_header X-Frame-Options "SAMEORIGIN" always;
+    add_header X-Content-Type-Options "nosniff" always;
+    add_header X-XSS-Protection "1; mode=block" always;
+    add_header Referrer-Policy "strict-origin-when-cross-origin" always;
+
+    # Upstream backend
+    upstream aoc_backend {
+        server backend:8000;
+    }
+
+    # HTTP → HTTPS redirect (optional; enable once TLS is configured)
+    # server {
+    #     listen 80;
+    #     server_name _;
+    #     return 301 https://$host$request_uri;
+    # }
+
+    server {
+        listen 80;
+        server_name _;
+
+        client_max_body_size 50M;
+        proxy_connect_timeout 60s;
+        proxy_send_timeout 60s;
+        proxy_read_timeout 60s;
+
+        location / {
+            proxy_pass http://aoc_backend;
+            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;
+            proxy_buffering off;
+        }
+    }
+
+    # HTTPS server (uncomment and configure once you have certificates)
+    # server {
+    #     listen 443 ssl http2;
+    #     server_name _;
+    #
+    #     ssl_certificate /etc/nginx/ssl/cert.pem;
+    #     ssl_certificate_key /etc/nginx/ssl/key.pem;
+    #     ssl_protocols TLSv1.2 TLSv1.3;
+    #     ssl_ciphers HIGH:!aNULL:!MD5;
+    #     ssl_prefer_server_ciphers on;
+    #
+    #     client_max_body_size 50M;
+    #
+    #     location / {
+    #         proxy_pass http://aoc_backend;
+    #         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;
+    #         proxy_buffering off;
+    #     }
+    # }
+}