[Enhancement] Playbook Mock-Page Unit Test Runner

[rickcedwhat-ai]

Problem Description

Validating playbook changes currently requires running the full end-to-end integration tests, which require databases, backends, and long execution times (3-7 minutes).

Proposed Solution

Expose a unit-testing harness that executes plays against static mock HTML strings or local templates:

import { testPlay } from '@rickcedwhat/playwright-sugar/test-utils';

test('branches correctly on readOnly page state', async () => {
  const mockHtml = '<button disabled>Save</button>';
  const result = await testPlay(projectPb.update, mockHtml);
  
  expect(result.outcome).toBe('readOnly');
});

This enables playbooks to be unit-tested in milliseconds.

[coderabbitai]

🔗 Related PRs

#26 - feat(play)!: third-arg outcome and Play.run lastOutcome [merged]
#27 - feat(playbook): add bindPlaybooks for multi-page catalog binding [merged]
#28 - feat(playbook): withCtx(name, ctx) log labels and bindPlaybooks { name } [merged]
#41 - feat: poc sync retry loop and timeout fixes [merged]
#46 - feat: simplify review errors, add debug mode config, and create playbook best practices doc [closed]

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[rickcedwhat-ai]

Blocked by #55 — this belongs in the future RBAC/playbook library, not in the core sugar primitives.