test: extend MCP UI test coverage with wizard, TOML, and error handling

## McpFormModal Component Tests (+5 tests)

### Infrastructure Improvements
- Enhance McpWizardModal mock from null to functional mock with testable onApply callback
- Refactor renderForm helper to support custom onSave/onClose mock injection
- Add McpServer type import for type-safe test data

### New Test Cases
1. **Wizard Integration**: Verify wizard generates config and auto-fills ID + JSON fields
   - Click "Use Wizard" → Apply → Form fields populated with wizard-id and config
   - Uses act() wrapper for React 18 async state updates

2. **TOML Auto-extraction (Codex)**: Test TOML → JSON conversion with ID extraction
   - Parse `[mcp.servers.demo]` → auto-fill ID as "demo"
   - Verify server object correctly parsed from TOML format
   - Codex-specific feature for config.toml compatibility

3. **TOML Validation Error**: Test missing required field handling
   - TOML with type="stdio" but no command → block submit
   - Display localized error toast: mcp.error.idRequired (3s duration)

4. **Edit Mode Immutability**: Verify ID field disabled during edit
   - ID input has disabled attribute and keeps original value
   - Config updates applied while enabled state preserved
   - syncOtherSide defaults to false in edit mode

5. **Error Recovery**: Test save failure button state restoration
   - Inject failing onSave mock → trigger error
   - Verify toast error displays translated message
   - Submit button disabled state resets to false for retry

## useMcpActions Hook Tests (+2 tests)

### New API Mocks
- Add syncEnabledToClaude and syncEnabledToCodex mock functions

### New Test Cases
1. **Backend Error Message Mapping**: Map Chinese error to i18n key
   - Backend: "stdio 类型的 MCP 服务器必须包含 command 字段"
   - Frontend: mcp.error.commandRequired (6s toast duration)

2. **Cross-app Sync Logic**: Verify conditional sync behavior
   - claude → claude: setEnabled called, syncEnabledToClaude NOT called
   - Validates sync only occurs when crossing app types

## Minor Changes
- McpPanel.test.tsx: Add trailing newline (formatter compliance)

## Test Coverage
- Test files: 17 (unchanged)
- Total tests: 112 → 119 (+7, +6.3%)
- Execution time: 3.20s
- All 119 tests passing ✅

tests/hooks/useMcpActions.test.tsx

@@ -17,6 +17,8 @@ const getConfigMock = vi.fn();
 const setEnabledMock = vi.fn();
 const upsertServerInConfigMock = vi.fn();
 const deleteServerInConfigMock = vi.fn();
+const syncEnabledToClaudeMock = vi.fn();
+const syncEnabledToCodexMock = vi.fn();
 
 vi.mock("@/lib/api", () => ({
   mcpApi: {
@@ -24,6 +26,8 @@ vi.mock("@/lib/api", () => ({
     setEnabled: (...args: unknown[]) => setEnabledMock(...args),
     upsertServerInConfig: (...args: unknown[]) => upsertServerInConfigMock(...args),
     deleteServerInConfig: (...args: unknown[]) => deleteServerInConfigMock(...args),
+    syncEnabledToClaude: (...args: unknown[]) => syncEnabledToClaudeMock(...args),
+    syncEnabledToCodex: (...args: unknown[]) => syncEnabledToCodexMock(...args),
   },
 }));
 
@@ -60,6 +64,8 @@ describe("useMcpActions", () => {
     setEnabledMock.mockReset();
     upsertServerInConfigMock.mockReset();
     deleteServerInConfigMock.mockReset();
+    syncEnabledToClaudeMock.mockReset();
+    syncEnabledToCodexMock.mockReset();
     toastSuccessMock.mockReset();
     toastErrorMock.mockReset();
 
@@ -239,4 +245,36 @@ describe("useMcpActions", () => {
     expect(captured).toBe(failure);
     expect(toastErrorMock).toHaveBeenCalledWith("delete failed", { duration: 6000 });
   });
+
+  it("maps backend error message when save fails with known detail", async () => {
+    const serverInput = createServer({ id: "input-id" });
+    const backendError = { message: "stdio 类型的 MCP 服务器必须包含 command 字段" };
+    upsertServerInConfigMock.mockRejectedValueOnce(backendError);
+    const { result } = renderUseMcpActions();
+
+    await expect(async () =>
+      result.current.saveServer("server-1", serverInput),
+    ).rejects.toEqual(backendError);
+
+    expect(toastErrorMock).toHaveBeenCalledWith("mcp.error.commandRequired", {
+      duration: 6000,
+    });
+  });
+
+  it("syncs enabled state to counterpart when appType is claude", async () => {
+    const server = createServer();
+    getConfigMock.mockResolvedValueOnce(mockConfigResponse({ [server.id]: server }));
+    const { result } = renderUseMcpActions();
+
+    await act(async () => {
+      await result.current.reload();
+    });
+
+    await act(async () => {
+      await result.current.toggleEnabled(server.id, true);
+    });
+
+    expect(setEnabledMock).toHaveBeenCalledWith("claude", server.id, true);
+    expect(syncEnabledToClaudeMock).not.toHaveBeenCalled();
+  });
 });