P3-G: Product Surface UX Contract

[github-actions]

Why: v1.0 needs an explicit UX contract for the standalone app while keeping the library surface headless and integration-first.

• P3-G1: Add docs/product-surfaces.md

  • Define app-vs-library scope, boundaries, and non-goals
  • Define standalone extension user journey: passive capture -> search -> revisit
  • Define what remains local-only and private in the app shell

• P3-G2: Add standalone search UX checklist to docs/product-surfaces.md

  • Search-first information architecture (query bar, results, lightweight metrics)
  • Result-card contract (title, URL, snippet/thumbnail, visit recency, relevance signal)
  • UX states: empty index, no matches, loading/indexing, error recovery

• P3-G3: Add model-mode UX contract to docs/product-surfaces.md

  • Nomic mode: multimodal recall (text + images in shared latent space)
  • Gemma mode: fine-grained text recall (no image embedding)
  • UI copy rules that make image-recall availability explicit by mode

• P3-G4: Add rabbit-hole recall acceptance checklist

  • Vague text recollection scenario recovers a previously visited page path
  • Vague visual recollection scenario recovers a previously seen image when Nomic mode is enabled
  • Add manual validation steps for model toggle behavior and capability messaging

Exit Criteria: Standalone app UX contract and model-mode behavior are documented; library boundary remains explicit and implementation-ready.