v0.43.0

• Add a provider-neutral, read-only Folder Tree with host-controlled selection, expansion and lazy loading; keyboard navigation, ancestor-preserving filters, load-state feedback and React bindings (#596, #598).
• Add structural Folder Tree Diff with host-provided changes, unified and aligned side-by-side views, status filters and change navigation. Matching, fetching and mutations remain host responsibilities (#597, #598).
• Add opt-in empty Number Input values with nullable events, placeholders, validation and form reset behavior, including React SSR/hydration (#594, #598). Existing numeric runtime defaults remain unchanged. NumberInput.value and value-change event types now include null; TypeScript consumers may need to narrow the value or use valueAsNumber.
• Ship core and all six framework adapters together at 0.43.0. Require core ^0.43.0 so React tree imports cannot resolve against an older core without the new entrypoints.
• Validation limitation: manual screen-reader acceptance for the tree and diff remains unfinished. Automated accessibility and Chromium interaction checks passed; the optional direct local Firefox tree/diff run could not launch its browser. These are not manual screen-reader or direct Firefox passes.