Initial scaffold: monorepo, widget, backend, CI/CD #4

WebAgent Implementation — Complete ✅

All 39 planned tasks across 8 phases are done.

✅ Phase 1-6: Scaffold (PR #6, merged)

• Widget: Preact + Shadow DOM, Vercel AI SDK agent loop, 5 tools, TF-IDF knowledge base, IndexedDB session store, WebMCP provider/consumer
• Backend: Hono on CF Workers, LLM proxy (BYOK + managed), fetch proxy, email queue, escalation, admin, KB
• CI/CD: typecheck/lint/test/build on PR, npm publish on release, wrangler deploy on push
• Security: XSS prevention, auth bypass fix, admin secret validation, safe URLs

✅ Phase 7: Testing (PR #9, merged)

• Widget: 23 tests (knowledge TF-IDF, session store, todo tool, type checks)
• Backend: 25 tests (health, auth, fetch proxy SSRF, email, escalate, admin, KB)
• 48 tests total, all passing

✅ Phase 8: Documentation (PR #9, merged)

• README with features, quick start, config reference, architecture diagram
• Skill authoring guide (docs/skills.md)
• Deployment guide (docs/deploy.md)