feat: add web app verification and QA handoff profile

[bradtaylorsf]

Summary

Add a web/app verification and QA handoff profile so hosted Alpha Loop can reliably build, preview, screenshot, and hand off websites or web applications for human review.

Why this matters

The first hosted use case is an Astro and Sanity marketing site. For this class of repo, success depends on local build/dev commands, browser verification, screenshots, preview URLs, console error capture, and clear QA checklists for humans. The hosted loop should make this easy without custom glue in every repo.

Proposed approach

• Add a documented web/app profile that standardizes setup, build, test, dev, preview, smoke test, screenshot, and QA checklist behavior.
• Capture Playwright/browser screenshots, console errors, network errors, and relevant local/staging URLs during verification.
• Include visual verification artifacts and QA instructions in PR bodies, session history, and qa.requested event payloads.
• Support an optional preview command or preview URL provider for services such as Vercel, Netlify, or a custom staging host without hard-coding any one provider.
• Provide defaults that work for Astro/React/Next-style apps while remaining generic.

Example config shape:

web_app:
  setup_command: pnpm install
  build_command: pnpm build
  test_command: pnpm test
  dev_command: pnpm dev
  dev_url: http://localhost:4321
  smoke_test: pnpm build
  screenshots:
    - name: home-desktop
      url: /
      viewport: desktop
    - name: home-mobile
      url: /
      viewport: mobile
  preview:
    command: ./scripts/get-preview-url.sh
    required: false

Acceptance criteria

• Web/app verification config supports setup, build, test, dev, dev URL, smoke test, screenshots, and preview URL discovery.
• Verification captures screenshots, console errors, network failures, and browser results into session history.
• PR bodies include preview links, screenshots or screenshot paths, and a human QA checklist when available.
• qa.requested events include exactly what a human should check.
• The profile works for a basic Astro marketing site without repo-specific Alpha Loop code changes.
• Preview integration remains provider-agnostic through commands or URLs.
• Tests cover config parsing, screenshot plan generation, QA payload generation, PR body content, and failure handling.

Out of scope

• Pixel-perfect visual regression testing as a required gate.
• Native Vercel/Netlify API clients.
• Production deployment.

Related

• Parent epic: Epic: Hosted Alpha Loop for 24/7 repo stewardship with human feedback loops #293
• Complements the existing Playwright/browser verification path.

[bradtaylorsf]

Part of #293