feat(driver): GET single driver's planning endpoint
refactor(driver-planning): expose personal-driver planning endpoint and service mapping
Summary of changes and features:
Routing Declared DriverPaths.DRIVER_PLANNING for the new per-driver route /api/user/driver.
API Added GET /api/user/driver/{id}/planning in DriverController, returning a DriverPlanningDTO populated via the service layer.
Service layer Extended DriverService with getDriverPlanning(Long id) and implemented it in DriverServiceImpl, reusing the planning DTO builder while enforcing driver-not-found checks.