feat: Add automated testing with Vitest and Playwright

- Install Vitest (integration tests for API routes) and Playwright (E2E tests)
- Add vitest.config.ts, playwright.config.ts, src/test/setup.ts
- Add test scripts: npm test, npm run test:e2e, npm run test:all
- Backend skill: writes integration tests for each API route
- QA skill: checks Playwright browser install, runs both suites,
  writes E2E tests from acceptance criteria as permanent regression suite
- Fix all skill frontmatter: remove unsupported context/agent/model/allowed-tools,
  fix argument-hint to be a quoted string
- Fix broken relative paths to docs/production/ in deploy and backend skills
- Update README with playwright install step and test script reference

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

.claude/skills/help/SKILL.md

@@ -1,10 +1,8 @@
 ---
 name: help
 description: Context-aware guide that tells you where you are in the workflow and what to do next. Use anytime you're unsure.
-argument-hint: [optional question]
+argument-hint: "optional question"
 user-invocable: true
-allowed-tools: Read, Glob, Grep, Bash
-model: opus
 ---
 
 # Project Help Guide