Materialize standalone paginated HTML

[JSv4]

Closes #438.

Depends on #500 and is intentionally based on agent/issue-437-export-architecture.

Summary

• adds the UI-free docxodus/export-browser materializer for complete, standalone paginated HTML
• snapshots caller bytes, validates the Add deterministic OOXML package manifests #493 package manifest/digest, enforces bounded resource and phase limits, and emits typed success/failure reports
• isolates conversion and two independent pagination passes, verifies determinism, sanitizes automatic resources and active content, normalizes IDs/fragment links, and reopens the serialized document offline before returning it
• binds the HTML, final-tree PageMap, renderer/runtime fingerprint, resource inventory, font observations, and report with SHA-256 digests
• fixes owner-part relationship resolution for header/footer/note/comment images, charts, and hyperlinks
• makes pagination use the supplied element's DOM realm and adds cooperative deadline/cancellation checks
• packages a closed 46-asset runtime graph, schemas, documentation, and a browser example

Verification

• npm run build
• npm run pretest — 163 package-boundary files
• Playwright integration gate — 27 passed
• PaginatedHeaderFooterContentTests — 3 passed
• HTML converter corpus — 53 passed
• independent final CSS tokenizer/sanitizer audit — clean

The Playwright workflow now uploads npm/playwright-report/ and npm/test-results/ with if: always(). Successful runs include directly viewable standalone HTML, PageMap/report JSON, request logs, offline-reopen screenshots, and a self-contained artifact viewer; expected strict/clipping failures retain their structured failed reports too.

Intentional follow-ups

• original-profile fidelity remains fail-closed pending [PDF] Add explicit revision and comment rendering profiles #444
• strict font verification remains fail-closed pending [PDF] Define and implement the font runtime contract #442
• oversized indivisible note/body flows remain fail-closed pending Footnote continuation stops at the paragraph: an oversized note paragraph is clipped, not split #489