feat(editor): add JSON format button to editors

Add one-click format functionality for JSON editors with toast notifications:

- Add format button to JsonEditor (CodeMirror)
- Add format button to CodexAuthSection (auth.json)
- Add format button to CommonConfigEditor (settings + modal)
- Add formatJSON utility function
- Add i18n keys: format, formatSuccess, formatError

Note: TOML formatting was intentionally NOT added to avoid losing comments
during parse/stringify operations. TOML validation remains available via
the existing useCodexTomlValidation hook.

src/i18n/locales/en.json

@@ -22,7 +22,10 @@
     "unknown": "Unknown",
     "enterValidValue": "Please enter a valid value",
     "clear": "Clear",
-    "toggleTheme": "Toggle theme"
+    "toggleTheme": "Toggle theme",
+    "format": "Format",
+    "formatSuccess": "Formatted successfully",
+    "formatError": "Format failed: {{error}}"
   },
   "apiKeyInput": {
     "placeholder": "Enter API Key",

src/i18n/locales/zh.json

@@ -22,7 +22,10 @@
     "unknown": "未知",
     "enterValidValue": "请输入有效的内容",
     "clear": "清除",
-    "toggleTheme": "切换主题"
+    "toggleTheme": "切换主题",
+    "format": "格式化",
+    "formatSuccess": "格式化成功",
+    "formatError": "格式化失败：{{error}}"
   },
   "apiKeyInput": {
     "placeholder": "请输入API Key",