test: investigate and fix failing edge-case suite (test_edge_cases.sh)

[T72]

Summary

The full safe test run now passes test_tm.sh but fails on tests/test_edge_cases.sh.

Observed

• Runner: bash tests/run_all_tests_safe.sh
• test_tm.sh: PASS (20/20)
• test_edge_cases.sh: FAIL (14 passed, 29 failed, total 43)

Impact

The full test pipeline stops at suite 2/12 and cannot provide confidence for release-quality behavior.

Proposed triage/fix

• Reproduce tests/test_edge_cases.sh directly in Windows/Git Bash context
• Identify first failing assertions and root causes
• Apply focused fixes preserving fail-fast behavior and clear diagnostics

[T72]

Resolved by PR #92 (test(windows): stabilize shell suites and safe runner in WSL).