feat: add Go MCP server list API (#15253)

## What
#15240 
Implements `GET /api/v1/mcp/servers` in the Go API server.

## Changes

- Added MCP server DAO list query with tenant scoping.
- Added MCP service response wrapper.
- Added MCP handler for list request parsing and response formatting.
- Wired `GET /api/v1/mcp/servers` under authenticated `/api/v1` routes.
- Initialized MCP service and handler in the Go server startup.
- update_time and update_date now both map to update_date
- create_time and create_date now both map to create_date
- default ordering now returns create_date
## API Behavior

Matches the Python endpoint behavior:

- Requires authenticated user.
- Lists MCP servers for the current user tenant.
- Supports `keywords`.
- Supports `mcp_id` and repeated/comma-separated `mcp_ids`.
- Supports `page`, `page_size`, `orderby`, and `desc`.
- Returns:

```json
{
  "code": 0,
  "message": "success",
  "data": {
    "mcp_servers": [],
    "total": 0
  }
}
```