- Rename compute_mode -> convert_model_for_vertex for clarity
- Move `import re` to module top-level (stdlib convention)
- Use greedy regex quantifier for more readable pattern matching
- Restore PEP 8 double blank line between top-level definitions
- Add test_client.py with 10 unit tests covering:
- Vertex disabled (env unset, "0", empty)
- Standard conversions (Opus, Sonnet, Haiku)
- Edge cases (already-converted, non-Claude, no date suffix, empty)
Follow-up improvements from PR #129 review.
Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
