Adds the proprietary all-rights-reserved license that applies to this
library. The text is identical to the engine LICENSE — this lib is
Tier-1 official platform content, distributed under the same terms.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
Previously, set_enabled(false) caused prev_click_down to drift, so a
click that spanned a disable/enable window would be silently dropped.
Move release-edge sync above early returns; handle click_action==nil
guard inline so is_action_down isn't called with nil.
