Additive TUI polish on top of v0.4.0 (patch, not a milestone bump).
Added
- First-launch welcome screen explaining the edit → save → advance loop and key shortcuts (shown once).
- Overall curriculum progress shown in the TUI alongside per-topic progress.
- A celebration screen when the whole curriculum is complete.
Fixed
- Finishing a single topic no longer shows the whole-curriculum "All exercises complete" header.