fix(filters): reject invalid coordinates; report rejections and the threshold profile

[joepetjr]

Summary

GPX-1 and GPX-2 from the portfolio remediation plan.

• Reject NaN, infinite and out-of-range (|lat|>90, |lon|>180) coordinates at intake, before the null-island and statistical tests. They are dropped, never clamped. Bounds are inclusive.
• Add filter_points_with_report and FilterReport: per-class rejected counts (all seven keys, in application order), an explicit outcome (ok, empty_input, all_rejected), and the effective threshold profile.
• Name the existing ground-vehicle defaults as GROUND_VEHICLE_PROFILE and make them the single source of the keyword defaults; a test asserts they cannot drift. A run with any changed threshold reports a custom profile, which means "your numbers", not "validated for an activity". No new activity profiles.
• filter_high_quality_points keeps its signature and return type and delegates to the report form. README and CHANGELOG updated.

Test plan

• Red first: both new test modules failed at import against origin/main (filter_points_with_report, GROUND_VEHICLE_PROFILE missing).
• Dispatcher re-run through the slot wrapper: 170 passed in 0.38s (all 7 test files named explicitly); default-config ruff already reports 37 findings on origin/main and CI does not run it, so the two new Optional[] hits follow the file's existing style
• CI runs pytest plus a no-runtime-deps check only; the repo configures no linter, so none was run.

Acceptance

• GPX-1: single-point NaN, inf and out-of-range inputs rejected on object, tuple and dict shapes; a mixed track keeps only the valid points as the original objects; all-invalid input reports all_rejected, distinct from empty_input; exact (0,0) is still dropped and counted as null_island; one-axis zeros survive.
• GPX-2: FilterReport.profile is set on every outcome, including empty and all-rejected; any non-default threshold reports custom; docs state only the ground-vehicle profile exists.