feat: Add MCP search server toggle with dedicated API architecture (#85)

* feat: add MCP search server toggle functionality

- Introduced `CLAUDE_MEM_MCP_ENABLED` setting to manage the MCP search server state.
- Updated `WorkerService` to handle MCP enabling/disabling based on the new setting.
- Enhanced `Sidebar` component to include a checkbox for toggling MCP search server.
- Modified `useSettings` hook to incorporate the new MCP setting.
- Updated default settings to include `CLAUDE_MEM_MCP_ENABLED` with a default value of true.
- Adjusted TypeScript types to include the new MCP setting.

* feat: Implement MCP toggle functionality in WorkerService and Sidebar

- Added API endpoints for MCP status retrieval and toggling in WorkerService.
- Updated Sidebar component to manage MCP toggle state and display status messages.
- Removed MCP_ENABLED from settings state management and default settings.
- Adjusted settings interface and related hooks to reflect the removal of MCP_ENABLED.

plugin/.mcp.json

@@ -1,3 +1,8 @@
 {
-  "mcpServers": {}
+  "mcpServers": {
+    "claude-mem-search": {
+      "type": "stdio",
+      "command": "${CLAUDE_PLUGIN_ROOT}/scripts/search-server.mjs"
+    }
+  }
 }