feat: deploy SearXNG search engine with Valkey rate limiting

- Add SearXNG service on port 6060 (replaces old port 11112)
- Add Valkey for rate limiting (5/min, 60/hour, 500/day)
- Add Nginx reverse proxy with X-Real-IP and X-Forwarded-For headers
- Configure JSON format and French locale
- Add rate limiting configuration in limiter.toml
- Add Valkey configuration in valkey.conf

proxy-config/nginx.conf

@@ -0,0 +1,22 @@
+events {
+    worker_connections 1024;
+}
+
+http {
+    upstream searxng {
+        server effi-searxng:8080;
+    }
+
+    server {
+        listen 6060;
+        server_name localhost;
+
+        location / {
+            proxy_pass http://searxng;
+            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;
+        }
+    }
+}