[autrin]

Great repo, Thanks!

Reference issue

Fixes #1490

What does this implement/fix?

Repeated target searches raise IndexError when the cached nearest waypoint
is the final course waypoint. The nearest-point search accesses ind + 1
before checking whether another waypoint exists.

Check the boundary before accessing the next waypoint and retain the final
index when the search reaches the course endpoint.

Add regression tests covering a single-waypoint course, repeated searches
at the final waypoint, progression to and beyond the endpoint, and repeated
searches at an interior waypoint. Document the endpoint behavior.

Additional information

Validation on Windows with Python 3.14.4:

• New regression tests against the original method: 3 failed, 1 passed.

• Updated Pure Pursuit tests: 6 passed.

• Full suite with MPLBACKEND=Agg:
  python -m pytest tests -l -Werror --durations=0
  160 passed, including the repository's code-style and mypy checks.

• Ruff on both changed Python files: passed.
• git diff --check: passed.

CheckList

• Did you add an unittest for your new example or defect fix?
• Did you add documents for your new example?
• All CIs are green?