test: add unit tests for `verification/`, `setup/`, `result/`

[KRRT7]

Parent: #2079

Phase 2 — Medium-low coverage modules (60–63%)

Module	Stmts	Current coverage
verification/	1,813	60%
setup/	803	62%
result/	340	63%

verification/

Key files:

• verification/pytest_plugin.py (331 stmts, 50%)
• verification/verifier.py (55 stmts, 45%)
• verification/parse_test_output.py (414 stmts, 62%)
• verification/comparator.py (463 stmts, 62%)
• verification/codeflash_capture.py (101 stmts, 21%)
• verification/coverage_utils.py (305 stmts, 70%)

setup/

Key files:

• setup/detector.py (459 stmts, 63%)
• setup/first_run.py (146 stmts, 64%)
• setup/config_writer.py (113 stmts, 59%)
• setup/config_schema.py (80 stmts, 58%)

result/

• result/explanation.py (80 stmts, 46%)
• result/create_pr.py (173 stmts, 67%)
• result/critic.py (87 stmts, 70%)

Target

100% coverage for these modules (~2,956 statements).