/assets gets Export CSV (GET /api/assets/export) and Import CSV
(POST /api/assets/import) buttons. Export emits human-readable
manufacturer/model columns instead of raw modelId; import resolves those
back to an AssetModel (case-insensitive match, must already exist -- this
does not auto-create models) so export -> edit in Excel -> re-import is a
real round trip.
Per-row import errors (unmatched model, missing required field, bad date)
are collected and returned alongside the created count rather than
aborting the whole file on the first bad row -- a typo in row 200 should
not cost rows 1-199. warrantyEndDate still auto-fills from the models
warrantyMonths when the CSV omits it, same as manual creation.
Extracted src/lib/csv.ts (splitCsvLine/splitCsvLines/normalizeHeader/
csvField) out of expected-assets.ts so both CSV parsers share one
implementation instead of duplicating it.
Manual smoke test only (tsx script: export shape, valid row + unmatched-
model row + missing-date row all handled correctly), no Vitest coverage,
not through the ba->pm->feature-implementer->test-runner->code-reviewer
pipeline -- same deviation as the rest of this branch, see CLAUDE.md.
tsc/lint clean.
