refactor(mcp): switch to user-level config ~/.claude.json and remove project-level logic

- Read/write ~/.claude.json (preserve unknown fields) for mcpServers
- Remove settings.local.json and mcp.json handling
- Drop enableAllProjectMcpServers command and UI toggle
- Update types, Tauri APIs, and MCP panel to reflect new status fields
- Keep atomic write and command validation behaviors

src/lib/tauri-api.ts

@@ -279,7 +279,7 @@ export const tauriAPI = {
     }
   },
 
-  // Claude MCP：获取状态（settings.local.json + mcp.json）
+  // Claude MCP：获取状态（用户级 ~/.claude.json）
   getClaudeMcpStatus: async (): Promise<McpStatus> => {
     try {
       return await invoke<McpStatus>("get_claude_mcp_status");
@@ -289,7 +289,7 @@ export const tauriAPI = {
     }
   },
 
-  // Claude MCP：读取 mcp.json 文本
+  // Claude MCP：读取 ~/.claude.json 文本
   readClaudeMcpConfig: async (): Promise<string | null> => {
     try {
       return await invoke<string | null>("read_claude_mcp_config");
@@ -299,16 +299,6 @@ export const tauriAPI = {
     }
   },
 
-  // Claude MCP：设置项目级启用开关
-  setClaudeMcpEnableAllProjects: async (enable: boolean): Promise<boolean> => {
-    try {
-      return await invoke<boolean>("set_claude_mcp_enable_all_projects", { enable });
-    } catch (error) {
-      console.error("写入 settings.local.json 失败:", error);
-      throw error;
-    }
-  },
-
   // Claude MCP：新增/更新服务器定义
   upsertClaudeMcpServer: async (
     id: string,