chore: add changeset for clearOnUnmount feature

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: RodrigoHamuy

.changeset/clear-path-on-unmount.md

@@ -0,0 +1,8 @@
+---
+"leva": minor
+---
+
+Add `clearOnUnmount` option to remove inputs from the store when their component unmounts.
+
+- `InputOptions.clearOnUnmount` — per-input flag; when `true` the input is removed from the store on unmount.
+- `LevaRootProps.clearOnUnmount` — panel-level flag; when `true` all inputs managed by that panel are cleared on unmount, overriding the per-input setting.