KChart v1.24.1 - Numeric LTTB Performance

Changed

• Added an internal numeric-field LTTB fast path that reads xField and yField directly.
• Preserved Date, string, nullish, mixed-value, and custom-accessor behavior without public API changes.
• Reduced the local 5M-point S1 median from roughly 106-109 ms to 33.7 ms in the verified benchmark environment.

Tests

• Added exact selected-point reference equivalence coverage across thresholds, ties, sparse/non-finite data, and custom accessor precedence.
• Added package export coverage to keep the optimized dispatch internal.
• Verified unit tests, adapter builds, demo build, package dry run, and 1M/5M benchmarks.