Replace all db.prepare() calls in mcp/index.ts, mcp/resources.ts, and
mcp/tools.ts with calls to the service layer. Add missing service functions:
- authService: isDemoUser, verifyMcpToken, verifyJwtToken
- adminService: isAddonEnabled
- atlasService: listVisitedCountries
- tripService: getTripSummary, listTrips with null archived param
Also fix getAssignmentWithPlace and formatAssignmentWithPlace to expose
place_id, assignment_time, and assignment_end_time at the top level, and
fix updateDay to correctly handle null title for clearing.
Add comprehensive unit and integration test suite for the MCP layer (821 tests all passing).