fix(design): persist pointer-driven layer reorders

[steve8708]

Fixes Layers-panel reorder drops that arrive with an empty dataTransfer payload during pointer-driven Chromium drags.

• fall back to the authoritative same-window drag state
• exercise the reorder with Playwright pointer events
• verify the reordered layers survive reload

Validation: git diff --check passed. Focused runtime tests could not run because workspace dependencies are not installed.

[github-actions]

Here's a visual recap of what changed:

Open the full interactive recap

[builder-io-integration]

Builder reviewed your changes and found 1 potential issue 🔴

Review Details

Incremental Code Review

The latest commit adds templates/design/app/components/design/LayersPanel.spec.ts to unit-test the drag-state fallback. The test intent is useful, but the new file currently imports canUseActiveDragStateForDrop and LayersPanelMoveIntent from ./LayersPanel even though neither symbol is defined or exported by the current LayersPanel.tsx. This causes the new Vitest/TypeScript test to fail at module/type resolution before the assertions can run.

The previously reviewed drag/drop implementation remains unchanged, and the added test is the only new functional delta. No browser verification was run because this incremental change is test-only and the prior dev-server setup remains unavailable due to the canvas dependency build failure.

🧪 Browser testing: Skipped — PR delta only adds a unit test; dev-server setup is also unavailable.

[builder-io-integration]

🔴 Export the helper and type used by the new test

The new spec imports canUseActiveDragStateForDrop and LayersPanelMoveIntent from ./LayersPanel, but the current LayersPanel.tsx does not define or export either symbol. Vitest/TypeScript will fail to resolve this test before executing it; add the helper/type to LayersPanel.tsx and export them, or update the test to use symbols that actually exist.