tune SearXNG VPN request timeouts and retries

docs/Dankclaw/SearXNG.md

@@ -61,9 +61,9 @@ valkey:
   url: "valkey://searxng-valkey:6379/0"
 
 outgoing:
-  request_timeout: 3.0
-  max_request_timeout: 10.0
-  retries: 3
+  request_timeout: 4.0
+  max_request_timeout: 12.0
+  retries: 1                     # avoid amplifying upstream 429/CAPTCHA responses
 ```
 
 ## Volumes
@@ -96,8 +96,11 @@ Reach SearXNG through Caddy (`search.dankclaw.local`) for browser use. A local s
 
 ## Unblocking Google & Search Providers
 
-SearXNG queries all ~50 upstream engines from one Gluetun VPN exit IP. The
-rate-sensitive engines (Google, DuckDuckGo) then answer with reCAPTCHA / 429,
+The current request policy allows a modest amount of VPN latency (`4.0s` per
+request, `12.0s` maximum) while limiting retries to one. This can recover slow
+providers, but it cannot fix an upstream CAPTCHA or 429 caused by the shared
+VPN exit IP. SearXNG queries all ~50 upstream engines from one Gluetun VPN exit
+IP. The rate-sensitive engines (Google, DuckDuckGo) then answer with reCAPTCHA / 429,
 and SearXNG **suspends** the offending engine for hours to days, which is what
 shows up as "Google went unavailable". This is upstream, not local.