refactor(mcp): improve UI consistency and i18n

- Add MCP-specific green button style (buttonStyles.mcp)
- Unify MCP panel and form buttons with emerald theme
- Adjust MCP entry button width to match AppSwitcher (px-3)
- Reduce JSON editor height from h-64 to h-48
- Update translations: "Add/Edit Server" → "Add/Edit MCP"
- Change form label to "MCP Title (Unique)" for clarity
- Move config wizard button to right side of JSON label
- Fix McpListItem enabled state check (explicit true check)

src/components/mcp/McpListItem.tsx

@@ -26,8 +26,8 @@ const McpListItem: React.FC<McpListItemProps> = ({
 }) => {
   const { t } = useTranslation();
 
-  // 默认启用
-  const enabled = server.enabled !== false;
+  // 仅当显式为 true 时视为启用；避免 undefined 被误判为启用
+  const enabled = server.enabled === true;
 
   // 只显示 description，没有则留空
   const description = (server as any).description || "";