test: test_tm.sh aborts at task ID extraction on tm add output

[T72]

Summary

The full test runner aborts in tests/test_tm.sh at Test 2 when extracting a task ID from tm add output.

Observed

• Command in test: TASK1=$(./tm add "First task" | grep -o '[a-f0-9]{8}')
• TASK1 becomes empty
• Because the script uses set -e, execution aborts immediately and the full suite stops.

Impact

• tests/run_all_tests_safe.sh exits early and does not execute remaining suites.

Proposed fix

• Make ID extraction robust to current tm output format.
• Preserve stop-on-first-failure behavior but emit clear failure diagnostics before exit.

[T72]

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