Schedule import: type column and artist-less rows

[chiptus]

Parent

Spec: non-music set types

What to build

Typed lineups import cleanly from CSV: an optional type column is validated (blank → null, invalid value → parse error). Named artist-less rows are kept and matched by name + date/stage against existing 0-artist sets only, so workshops survive re-imports without duplication. On re-import, an explicit type overwrites the stored type while a blank preserves it. The diff review shows type chips so changes are verifiable before commit.

Acceptance criteria

• type column parsing: blank → null, valid values accepted, invalid values produce a parse error (unit tests at the CSV-parse seam)
• Named artist-less rows import; re-import matches them by name + date/stage against 0-artist sets only (unit tests at the commit-payload seam)
• Explicit type overwrites on re-import; blank keeps the stored type
• Type chips appear in the diff review

Blocked by

• Set type foundation