Add verify_receipt method support to Go templates:
- client.go.tera: Add verify_receipt with string params (path, receipt)
- conformance_test.go.tera: Add testVerifyReceipt test case
Code generator cleanup:
- Add uses_string_params and string_param_count to Method struct
- Fix unused variable warnings in contract parsing
- Document TODO for full markdown contract parsing
Verification:
- All 9 methods generated correctly (extract, extract_text, extract_markdown, extract_stream, search, get_metadata, hash, classify, verify_receipt)
- All 7 error types generated with exit code mapping
- Drift detection working (validate command)
- Protection against overwriting hand-written code (GENERATED marker)
See notes/pdftract-1534.md for full acceptance criteria status.
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
Bead-Id: pdftract-1534
