Add --cwd <path> / --cwd=<path> support so sandboxed subagents running
outside the project root can target a specific directory. Invalid paths
return a clear error. Tests ported to tests/state.test.cjs (the old
monolithic test file was split into domain files on main).
Closes#622
Co-Authored-By: Colin Johnson <colin@solvely.net>
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
Move 81 tests (18 describe blocks) from single monolithic test file
into 7 domain-specific test files under tests/ with shared helpers.
Test parity verified: 81/81 pass before and after split.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
