ford-obd: ELM327 OBD-II reader + 6.0 Power Stroke no-start triage

Read stored/pending/permanent DTCs, decode with 6.0-relevant codes flagged,
guarded mode-04 clear (--clear), key live PIDs + battery voltage, and a
6.0 no-start triage checklist. Tested against a CH340 ELM327 v1.5 adapter.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_016yT89n4zR4qbrySoSiEyZs

.gitignore

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+*.pyc
+.venv/