refactor(util, executor): optimize payload handling and schema processing

- Replaced repetitive string operations with a centralized `escapeGJSONPathKey` function.
- Streamlined handling of JSON schema cleaning for Gemini and Antigravity requests.
- Improved payload management by transitioning from byte slices to strings for processing.
- Removed unnecessary cloning of byte slices in several places.

internal/util/translator.go

@@ -6,7 +6,6 @@ package util
 import (
 	"bytes"
 	"fmt"
-	"strings"
 
 	"github.com/tidwall/gjson"
 	"github.com/tidwall/sjson"
@@ -33,15 +32,15 @@ func Walk(value gjson.Result, path, field string, paths *[]string) {
 			// . -> \.
 			// * -> \*
 			// ? -> \?
-			var keyReplacer = strings.NewReplacer(".", "\\.", "*", "\\*", "?", "\\?")
-			safeKey := keyReplacer.Replace(key.String())
+			keyStr := key.String()
+			safeKey := escapeGJSONPathKey(keyStr)
 
 			if path == "" {
 				childPath = safeKey
 			} else {
 				childPath = path + "." + safeKey
 			}
-			if key.String() == field {
+			if keyStr == field {
 				*paths = append(*paths, childPath)
 			}
 			Walk(val, childPath, field, paths)
@@ -87,15 +86,6 @@ func RenameKey(jsonStr, oldKeyPath, newKeyPath string) (string, error) {
 	return finalJson, nil
 }
 
-func DeleteKey(jsonStr, keyName string) string {
-	paths := make([]string, 0)
-	Walk(gjson.Parse(jsonStr), "", keyName, &paths)
-	for _, p := range paths {
-		jsonStr, _ = sjson.Delete(jsonStr, p)
-	}
-	return jsonStr
-}
-
 // FixJSON converts non-standard JSON that uses single quotes for strings into
 // RFC 8259-compliant JSON by converting those single-quoted strings to
 // double-quoted strings with proper escaping.