Clarify GTFS-RT time and delay handling

[chtitux]

This commit implements two major improvements to the library:

1. GTFS-RT Time/Delay Support:

   • Added arrival_time and departure_time fields to StopTimeRealtime type
   • Updated mergeRealtimeData in stop-times.ts to query and export both time and delay fields
   • Now exports complete GTFS-RT information as per specification

2. Unified Filter-Based API:

   • Removed all getXXXByYYYY methods in favor of unified getXXXX methods with optional filters
   • All filter parameters now support both single values and arrays
   • Simplified API surface and improved consistency:
     • stops.ts: Removed getStopById, getStopByCode, getStopsByTrip, getAllStops
     • routes.ts: Removed getRouteById, getRoutesByAgency, getAllRoutes - trips.ts: Removed getTripById, getTripsByRoute, getTripsByRouteAndService, getTripsByRouteServiceAndDirection, getTripsByService - agencies.ts: Removed getAgencyById, getAllAgencies - stop-times.ts: Removed getStopTimesByTrip, getStopTimesByStop, getStopTimesByStopAndTrips, getStopTimesForStopRouteDirection - rt-stop-time-updates.ts: Removed getStopTimeUpdatesByTripId - gtfs-sqljs.ts: Removed wrapper methods for getXXXByYYYY, updated to use filters
   • Kept specialized methods like searchStopsByName that can't be merged into filters

3. Updated Tests:

   • Migrated all tests to use new filter-based API
   • Added tests for array filter support
   • All 81 tests passing

The new API is more flexible and consistent. For example:

• Old: getStopById('STOP1') → New: getStops({ stopId: 'STOP1' })[0]
• New: getStops({ stopId: ['STOP1', 'STOP2'] }) for multiple stops

Note: Documentation (README and website) still needs to be updated with the new API examples.