fix(ci): allow generated Turtle EOF blank lines

[pedropaulofb]

Summary

The final PR-state validation was failing because Git's default blank-at-eof check rejected the established blank line emitted by the repository's generated Turtle files.

Changes

• Allow generated Turtle files to contain a blank line at EOF during final PR validation.
• Preserve checks for trailing spaces and spaces before tabs.
• Add regression coverage confirming that generated EOF blank lines are accepted while real trailing whitespace is rejected.

No generated model artifacts or workflow files were modified.

Validation

• 526 Python tests passed.
• The exact PR Add leblanc2026rocap #370 base-to-head whitespace check passed.
• Generated model outputs remained unchanged.
• Catalog and release validation passed.
• All workflow YAML files parsed successfully.