Simplify tarpit implementation for HAProxy 3.0 compatibility

- Remove unsupported set-timeout tarpit directives
- Use fixed 30s global tarpit timeout (reduced from 60s)
- Keep escalation tracking via gpc1 for monitoring repeat offenders
- HAProxy 3.0 doesn't support variable tarpit timeouts per request

The escalation level (gpc1) is still tracked and visible in monitoring
but all tarpits use the same 30s delay.

🤖 Generated with [Claude Code](https://claude.ai/code)

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

templates/hap_header.tpl

@@ -45,6 +45,6 @@ defaults
     timeout server          10m
     timeout http-keep-alive 120s
     timeout check           10s
-    timeout tarpit          60s  # Maximum tarpit time for exploit scanners
+    timeout tarpit          30s  # Tarpit delay for detected scanners (fixed in HAProxy 3.0)
     maxconn                 3000