feat: add permission-denied dialog for macOS network/mic access

When macOS denies network access (PermissionDenied), show a localized
dialog explaining how to grant permission in System Settings, with
an 'Open System Settings' button that opens directly to the Local
Network privacy pane.

Also adds author info (Edison Jwa) to About dialog and moves
diagnostics button from AppBar into About dialog.

apps/chanora_flutter/lib/l10n/app_zh.arb

@@ -18,6 +18,7 @@
   "diagnosticsAction": "诊断信息",
   "aboutAction": "关于",
   "aboutVersion": "版本 {version}",
+  "aboutAuthor": "作者: Edison Jwa",
   "aboutNonAffiliation": "Chanora 是独立项目，与 TeamSpeak 之间不存在任何附属、认可、赞助或官方关联关系。",
   "aboutLicenseHeading": "许可协议",
   "aboutLicenseBody": "Chanora 采用 Apache License 2.0 或 MIT License 双协议授权，使用者可任选其一。完整协议文本以 LICENSE-APACHE 与 LICENSE-MIT 形式随仓库一同分发。",
@@ -111,5 +112,11 @@
     "placeholders": {
       "message": { "type": "String" }
     }
-  }
+  },
+  "networkPermissionTitle": "需要网络权限",
+  "networkPermissionBody": "Chanora 需要网络访问权限。请前往系统设置 → 隐私与安全性 → 本地网络，启用 Chanora，然后重试。",
+  "networkPermissionOpenSettings": "打开系统设置",
+  "microphonePermissionTitle": "需要麦克风权限",
+  "microphonePermissionBody": "Chanora 需要麦克风访问权限。请前往系统设置 → 隐私与安全性 → 麦克风，启用 Chanora。",
+  "permissionDenied": "权限被拒绝"
 }