docs: resolve car integration spec quality checklist (65/65 items)

All checklist items validated against spec, plan, and implementation:
- 61 items checked off with clarification notes
- 4 items marked N/A (map features deferred, distribution out of scope)
- Zero items remain unresolved

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: jamesarich