Complete contract tests for all commands

Write contract tests for commands missing test coverage.

**Missing tests** (from 001-T009-T014):
- [ ] `light up` command
- [ ] `light deploy` command (blocked by #1)
- [ ] `light status` command
- [ ] `light logs` command
- [ ] `light down` command

**Completed**: `light init` (001-T009) ✅

**Approach**: File operations only, no Docker (per testing strategy)

**Related**: Phase 3.2 from spec 001