fix(clearance): render sw keepalive diagnostic evidence

[ChechiDev]

Summary

• Adds sw_keepalive_alarm_present and sw_keepalive_alarm_error_type to _SAFE_EVIDENCE_KEYS in cli/main.py
• Display-only change — no smoke gate behavior changed, no CDP/browser logic touched
• Enables distinguishing sw_unreachable (CDP target not found) from False (alarm absent) in CLI output when sw_keepalive_confirmed blocks
• No real smoke executed during this change

Closes #205

Test plan

• uv run pytest tests/unit/cli/test_main_real_clearance_wireup.py::TestSwKeepaliveEvidenceRendering — 3 new tests GREEN
• uv run pytest tests/unit/cli/ -q — no regressions beyond pre-existing failures
• uv run ruff check . — clean
• uv run flake8 . — clean