ci(storybook): wire test:storybook into CI (#1251) (#1297)

* ci(storybook): wire test:storybook into CI (#1251)

- Add test:storybook:watch to clients/web for interactive iteration; the
  one-shot script already existed.
- Surface test:storybook at the repo root, delegating to the web client.
- Add a separate CI step that installs the Playwright Chromium binary
  and runs the storybook play-function suite after validate. Kept out of
  validate because the suite needs a real browser and is ~10s slower
  than the unit tests.
- Document the new pre-push step in AGENTS.md.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

* ci(storybook): cache Playwright browsers + tighten AGENTS wording

Cache the Chromium binary keyed on clients/web/package-lock.json so the
~150MB download is a no-op on CI cache hits. Also clarify that CI runs
test:storybook after the unit/lint/build checks (not literal `validate`,
which is a local-only script).

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

---------

Co-authored-by: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

AGENTS.md

@@ -77,6 +77,7 @@ All work should be driven by items on the project board.
 
 ### Lint-fixed, Formatted code
 - ALWAYS do `npm run validate` before pushing any changes, this runs the various lint, build, format checks, etc.
+- Also run `npm run test:storybook` before pushing — it executes every story's `play` function in headless Chromium via `@vitest/browser-playwright` (~10s). CI runs this as a separate step after the unit/lint/build checks; failures block merge. It is kept out of `validate` because it needs the Playwright browser binary and is much slower than the unit suite.
 
 ### Typescript instructions
 - Use TypeScript for all new code