- New /codes dashboard page (behind the session login, linked in the top bar):
lists every mapping by kind with Add, inline Edit+Save and Delete. Sam can put
real teacher surnames in without a rebuild (FR-17).
- Decode timetable EVENTS through the same map as periods, so an ensemble reads
'JAZZ ENSEMBLE - Ensemble Room - Mr KWO' instead of raw codes.
- teacherName splits comma- or space-separated codes ('HHL, OFG').
- SeedCodes is a one-time bootstrap while the table is empty, so a correction or
a delete is never overwritten or restored.
- Tests: decode Label/Event, the /codes page (save, refuse, csrf, delete, auth),
store re-seed behaviour. go test ./internal/... passes.
Sam Rolfe
3e25011399