test: Add SpectraMax 340PC-384 kinetic partial plate test case

Sanitized test file exercising all the newly supported format features:
Latin-1 encoding, M:SS time format, empty group blocks with no data,
no GroupColumns section, and partial plate with unused wells.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: nathan-stender