Verify that cargo nextest timeout configuration is complete and correct.
All three profiles (default, ci, ci-proptest) have proper slow-timeout
and terminate-after settings to prevent test hangs.
Closes bf-5i310
Acceptance criteria:
- PASS: all profiles have slow-timeout configured
- PASS: all profiles have terminate-after set
- PASS: configuration is well-documented with rationale
- PASS: timeout enforcement is active
Verification: notes/bf-5i310.md
