feat(schedule): retain static GTFS journey timing

[adot-7]

Closes #76

Summary

• retain validated GTFS stop times, service IDs, calendar rules, and optional exceptions
• add deterministic Delhi-local scheduled journey timing on the existing BFS route, including explicit transfer compatibility/unavailable states
• add compact SCHEDULED / NEXT SERVICE sidebar summary and expandable stop detail
• document/test expired 2025-12-31 weekly calendar carry-forward as estimated scheduled demo data

Tests

• gofmt -w ...
• go test ./...
• go vet ./...
• go build ./...
• git diff --check

No realtime or vehicle-position claims are made.