build(web): replace Playwright MCP with project-scoped Playwright CLI

- feat: add `.agents/skills/playwright-cli/` with complete Skill
  markdown, agent interface, and 9 reference files covering session
  management, spec-driven testing, video recording, tracing, storage,
  request mocking, element attributes, test debugging, and running
  custom code
- feat: add `.playwright/cli.config.json` to configure the Playwright
  CLI
- feat: add `web/package.json` `playwright:cli` script that resolves
  `playwright cli` from the repo root
- build: remove `@playwright/mcp` dependency from `web/package.json`
- build: set `XDG_CACHE_HOME` in `mise.toml`
- build: delete `.codex/config.toml` (MCP server config)
- docs: update `README.md`, `docs/web/roadmap.md`,
  `docs/web/decisions.md`, and `web/README.md` to reflect the new
  Playwright CLI approach

docs/web/roadmap.md

@@ -37,7 +37,7 @@ The project foundation contains:
 - Oxlint from the Vite template
 - Vitest for framework-independent client and session tests
 - Playwright Test with a headless Chromium smoke test
-- Project-scoped Playwright MCP for interactive browser debugging
+- Project-scoped Playwright CLI and repository Skill for interactive browser debugging
 
 Ant Design owns reusable UI components and theme tokens. Tailwind CSS is initially limited to application layout, spacing, and responsive utilities.