burn: Fix crisis backend tests, gateway injection, and nginx rate limiting

- Fixed test imports (relative → absolute package imports)
- Added conftest.py for pytest path configuration
- Fixed get_system_prompt() to inject crisis context when detected
- Added pytest.ini configuration
- Expanded tests: 49 tests covering detection, response, gateway, edge cases, router
- Added deploy/rate-limit.conf for nginx http block inclusion
- Updated nginx.conf with correct zone name and limit_req_status 429
- Updated BACKEND_SETUP.md with complete setup instructions

deploy/nginx.conf

@@ -1,5 +1,9 @@
 # The Door — nginx config for alexanderwhitestone.com
 # Place at /etc/nginx/sites-available/the-door
+#
+# IMPORTANT: Also include deploy/rate-limit.conf in your main
+# /etc/nginx/nginx.conf http block:
+#   include /etc/nginx/sites-available/the-door/deploy/rate-limit.conf;
 
 server {
     listen 80;
@@ -57,15 +61,14 @@ server {
         chunked_transfer_encoding on;
         proxy_read_timeout 300s;
 
-        # Rate limiting
-        limit_req zone=api burst=5 nodelay;
+        # Rate limiting — 10 req/min per IP, burst of 5
+        # Zone must be defined in nginx http block — see deploy/rate-limit.conf
+        limit_req zone=the_door_api burst=5 nodelay;
+        limit_req_status 429;
     }
 
     # Health check
     location /health {
         proxy_pass http://127.0.0.1:8644/health;
     }
-
-    # Rate limit zone (define in http block of nginx.conf)
-    # limit_req_zone $binary_remote_addr zone=api:10m rate=10r/m;
 }