Summary

• add delayed hover previews for Pages, Templates, and Components in Site Explorer
• render the current in-memory draft through the existing CMS runtime-preview boundary at a fixed 1440 × 900 desktop viewport, scaled into a compact 320px card
• keep previews scrollable while hovered, with loading, error, and retry states
• share runtime preview document generation with the full-page preview overlay

Why

Site Explorer rows currently require opening an item to understand its visual output. Hover previews make pages, templates, and components scannable without changing the active canvas or switching to a mobile layout.

Screenshot

The screenshot uses an imported production-style landing page to demonstrate that the preview preserves the 1440px desktop composition inside the 320px card.

Verification

• bun test src/__tests__/site-explorer/siteExplorerPanel.test.tsx src/__tests__/publisher/previewOverlay.test.tsx — 71 passed
• bun test src/__tests__/architecture/css-token-policy.test.ts src/__tests__/architecture/no-css-var-fallbacks.test.ts src/__tests__/architecture/noTailwindUtilities.test.ts src/__tests__/architecture/button-primitive-usage.test.ts src/__tests__/architecture/admin-router-usage.test.ts src/__tests__/architecture/no-core-barrel-deep-imports.test.ts — 11 passed
• bunx tsc -b --pretty false
• bun run lint --no-cache
• browser smoke: page, template, and component previews; real-site rendering; internal iframe scroll from 0 to 697px; symmetrical 4px shell padding