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/rules/rules_bench_test.go

@@ -0,0 +1,74 @@
+package rules
+
+import (
+	"bytes"
+	"io"
+	"net/http"
+	"net/url"
+	"testing"
+)
+
+func BenchmarkRules(b *testing.B) {
+	var rules Rules
+	err := parseRules(`
+- name: admin-api
+  on: |
+    path glob(/api/admin/*)
+    header Authorization
+    method POST
+  do: |
+    set resp_header X-Access-Level "admin"
+    set resp_header X-API-Version "v1"
+- name: user-api
+  on: |
+    path glob(/api/users/*) & method GET
+  do: |
+    set resp_header X-Access-Level "user"
+    set resp_header X-API-Version "v1"
+- name: public-api
+  on: |
+    path glob(/api/public/*) & method GET
+  do: |
+    set resp_header X-Access-Level "public"
+`, &rules)
+	if err != nil {
+		b.Fatal(err)
+	}
+
+	upstream := http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.WriteHeader(http.StatusOK)
+	})
+
+	b.Run("BuildHandler", func(b *testing.B) {
+		for b.Loop() {
+			rules.BuildHandler(upstream)
+		}
+	})
+
+	b.Run("RunHandler", func(b *testing.B) {
+		var r = &http.Request{
+			Body: io.NopCloser(bytes.NewReader([]byte(""))),
+			URL:  &url.URL{Path: "/api/users/"},
+		}
+		var w noopResponseWriter
+		handler := rules.BuildHandler(upstream)
+		b.ResetTimer()
+		for b.Loop() {
+			handler.ServeHTTP(w, r)
+		}
+	})
+}
+
+type noopResponseWriter struct {
+}
+
+func (w noopResponseWriter) Header() http.Header {
+	return http.Header{}
+}
+
+func (w noopResponseWriter) Write(b []byte) (int, error) {
+	return len(b), nil
+}
+
+func (w noopResponseWriter) WriteHeader(int) {
+}