Clean up AI plugin translations and add copiedSuccess

- Remove unused 'language' key from ai.settings (plugin no longer has language option)
- Add 'copiedSuccess' message for clipboard copy feedback
- Ensure consistency between English and Chinese translations

Plugin language is now fully controlled by main app settings,
with no duplicate language selection in plugin UI.

Author: KariHall619

console/atest-ui/src/locales/en.json

@@ -98,7 +98,6 @@
         "subtitle": "Natural language to SQL query generator",
         "settings": {
             "title": "Settings",
-            "language": "Language",
             "provider": "Provider",
             "endpoint": "Endpoint",
             "model": "Model",
@@ -153,7 +152,8 @@
             "configSaveFailed": "Saved locally, backend sync failed",
             "connectionSuccess": "Connection successful!",
             "connectionFailed": "Connection failed",
-            "generating": "Generating SQL..."
+            "generating": "Generating SQL...",
+            "copiedSuccess": "Copied to clipboard"
         }
     },
     "//see http spec": "https://developer.mozilla.org/en-US/docs/Web/HTTP/Status/403",

console/atest-ui/src/locales/zh.json

@@ -94,7 +94,6 @@
         "subtitle": "自然语言转SQL查询生成器",
         "settings": {
             "title": "设置",
-            "language": "语言",
             "provider": "提供者",
             "endpoint": "端点",
             "model": "模型",
@@ -149,7 +148,8 @@
             "configSaveFailed": "本地保存成功，后端同步失败",
             "connectionSuccess": "连接成功！",
             "connectionFailed": "连接失败",
-            "generating": "生成SQL中..."
+            "generating": "生成SQL中...",
+            "copiedSuccess": "已复制到剪贴板"
         }
     },
     "httpCode": {