Add dev environment: debug subdomain, IP restriction, separate container

- Add debug.killmybacklog.com nginx config (IP-restricted to 164.215.8.152)
- Add django-dev container on port 8081 in docker-compose
- Add dev branch pipeline step deploying to django-dev
- Add killmybacklog.com and debug subdomain to ALLOWED_HOSTS/CSRF origins

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

nginx/debug.killmybacklog.com.conf

@@ -0,0 +1,34 @@
+server {
+    listen 80;
+    listen [::]:80;
+    server_name debug.killmybacklog.com;
+    return 301 https://$host$request_uri;
+}
+
+server {
+    listen 443 ssl;
+    listen [::]:443 ssl;
+    server_name debug.killmybacklog.com;
+
+    ssl_certificate     /etc/letsencrypt/live/debug.killmybacklog.com/fullchain.pem;
+    ssl_certificate_key /etc/letsencrypt/live/debug.killmybacklog.com/privkey.pem;
+    include /etc/letsencrypt/options-ssl-nginx.conf;
+    ssl_dhparam /etc/letsencrypt/ssl-dhparams.pem;
+
+    client_max_body_size 10m;
+
+    allow 164.215.8.152;
+    deny all;
+
+    location = / {
+        return 301 /backlogger/;
+    }
+
+    location / {
+        proxy_pass http://127.0.0.1:8081;
+        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;
+    }
+}