feat(rules): add post-request rules system with response manipulation (#160)

* Add comprehensive post-request rules support for response phase
* Enable response body, status, and header manipulation via set commands
* Refactor command handlers to support both request and response phases
* Implement response modifier system for post-request template execution
* Support response-based rule matching with status and header checks
* Add comprehensive benchmarks for matcher performance
* Refactor authentication and proxying commands for unified error handling
* Support negated conditions with !
* Enhance error handling, error formatting and validation
* Routes: add `rule_file` field with rule preset support
* Environment variable substitution: now supports variables without `GODOXY_` prefix

* new conditions:
  * `on resp_header <key> [<value>]`
  * `on status <status>`
* new commands:
  * `require_auth`
  * `set resp_header <key> <template>`
  * `set resp_body <template>`
  * `set status <code>`
  * `log <level> <path> <template>`
  * `notify <level> <provider> <title_template> <body_template>`

internal/route/routes/context.go

@@ -86,6 +86,13 @@ func TryGetUpstreamPort(r *http.Request) string {
 	return ""
 }
 
+func TryGetUpstreamHostPort(r *http.Request) string {
+	if u := tryGetURL(r); u != nil {
+		return u.Host
+	}
+	return ""
+}
+
 func TryGetUpstreamAddr(r *http.Request) string {
 	if u := tryGetURL(r); u != nil {
 		return u.Host