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

searxng-config/valkey.conf

@@ -0,0 +1,26 @@
+# Redis configuration for SearXNG rate limiting
+bind 0.0.0.0
+protected-mode no
+port 6379
+tcp-backlog 511
+timeout 0
+tcp-keepalive 300
+daemonize no
+supervised no
+pidfile /var/run/redis_6379.pid
+loglevel notice
+databases 1
+save 900 1
+save 300 10
+save 60 10000
+stop-writes-on-bgsave-error yes
+rdbcompression yes
+rdbchecksum yes
+dbfilename dump.rdb
+dir /data
+appendonly no
+appendfilename "appendonly.aof"
+hz 10
+dynamic-hz yes
+aof-rewrite-incremental-fsync yes
+rdb-save-incremental-fsync yes