Implements enrichment for HAFAS API responses by cross-referencing
section data against an indexed ÖBB GTFS feed.
This involves adding logic to fetch, parse, and index the GTFS data
from the specified URL. The enrichment function now uses GTFS time
and station data to populate `gtfsName` and `gtfsDirection` fields
for missing journey data in HAFAS responses.
Updates are also made to:
- Update `apps/web/src/lib/constants.ts` with the GTFS URL.
- Create `apps/web/src/lib/oebb-gtfs.ts` to handle GTFS fetching and indexing.
- Enhance `apps/web/src/app/api/hafas/route.ts` to utilize the new
enrichment function.
-Package updates include `fflate` and minor fixes to other packages.
fegger