refactor(rules): introduce block DSL, phase-based execution, and flow validation

- add block syntax parser/scanner with nested @blocks and elif/else support
- restructure rule execution into explicit pre/post phases with phase flags
- classify commands by phase and termination behavior
- enforce flow semantics (default rule handling, dead-rule detection)
- expand HTTP flow coverage with block + YAML parity tests and benches
- refresh rules README/spec and update playground/docs integration

internal/route/rules/check_on.go

@@ -1,21 +1,25 @@
 package rules
 
-import "net/http"
+import (
+	"net/http"
+
+	httputils "github.com/yusing/goutils/http"
+)
 
 type (
-	CheckFunc func(w http.ResponseWriter, r *http.Request) bool
+	CheckFunc func(w *httputils.ResponseModifier, r *http.Request) bool
 	Checker   interface {
-		Check(w http.ResponseWriter, r *http.Request) bool
+		Check(w *httputils.ResponseModifier, r *http.Request) bool
 	}
 	CheckMatchSingle []Checker
 	CheckMatchAll    []Checker
 )
 
-func (checker CheckFunc) Check(w http.ResponseWriter, r *http.Request) bool {
+func (checker CheckFunc) Check(w *httputils.ResponseModifier, r *http.Request) bool {
 	return checker(w, r)
 }
 
-func (checkers CheckMatchSingle) Check(w http.ResponseWriter, r *http.Request) bool {
+func (checkers CheckMatchSingle) Check(w *httputils.ResponseModifier, r *http.Request) bool {
 	for _, check := range checkers {
 		if check.Check(w, r) {
 			return true
@@ -24,7 +28,7 @@ func (checkers CheckMatchSingle) Check(w http.ResponseWriter, r *http.Request) b
 	return false
 }
 
-func (checkers CheckMatchAll) Check(w http.ResponseWriter, r *http.Request) bool {
+func (checkers CheckMatchAll) Check(w *httputils.ResponseModifier, r *http.Request) bool {
 	for _, check := range checkers {
 		if !check.Check(w, r) {
 			return false