fix: Thermo Skanit - Initialize plate_well_count to prevent UnboundLocalError

When processing plates with empty wavelength data, the plate_well_count variable was never assigned, causing an UnboundLocalError when trying to access it later. This fix initializes plate_well_count to 0 at the start of each plate iteration, ensuring the variable is always defined even when no valid data is found.

This follows the established pattern in other parsers (e.g., QIAcuity dPCR) where 0 is used as a fallback value when plate well count cannot be determined, since the field is required in the ASM schema.

Co-Authored-By: Claude Opus 4.1 <noreply@anthropic.com>

Author: nathan-stender

src/allotropy/parsers/thermo_skanit/thermo_skanit_structure.py

@@ -321,6 +321,7 @@ def create(
         plate_well_counts: dict[str, int] = {}
 
         for plate in plates:
+            plate_well_count = 0  # Initialize to 0 in case no valid data is found
             for wavelength, data_df in plate.wavelength_data.items():
                 if data_df.empty:
                     continue