feat: add source-pinned Penpot design-system bindings

[igor-im]

Adds source-pinned Penpot bindings for 42 Chatbot, Code, Voice, and Utilities component families (286 variants), linked consumer fixtures, reference PNGs, and a local implementation lab. Includes the Audio Player SSR alignment, explicit React Flow test-fixture dimensions, and the Open in Chat example context correction.

The Test workflow now runs a dedicated Penpot binding gate with complete Git history, a frozen dependency lockfile, resolver tests, and source/manifest validation. Preserve branch history with a merge commit because the Audio Player binding references a commit on this branch.

Validation on commit 302bbb6447ae6339afb3aa32289a1583628d7c46: all five CI jobs passed, covering the binding gate, package/docs build, and application tests on Node 20, 22, and 24. The binding suite has 20 tests covering all 286 combinations and checked-in consumer fixtures; the manifest validator accepts all 42 entries.

Previous section records document published Penpot components and linked consumer proofs. Live shadcn dependency verification remains pending because the Penpot MCP plugin is disconnected. Workflow's seven families remain staged until that dependency audit is complete. This PR integrates into igor-im/ai-elements/main; upstream PR vercel#495 is closed without merging. The fork's Test workflow is active, while its upstream publishing and Generate Skills workflows remain disabled.