Pins the parse_lastpass_csv signature and ImportWarning shape.
A single LastPass row with name/url/username/password round-trips
to a Login item with a freshly-minted ID. Header validation
rejects shape mismatches with a clear message.
TOTP, grouping, fav, SecureNote rows, and error paths land in
Tasks 3-6.
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
