Generated App CI: emit default workflow template for app-level tests

[snissn]

Background
To make generated-app tests actually useful, generated repos need a default CI workflow.

Scope

• Emit optional GitHub Actions workflow template with generated apps.
• Workflow should run:
  • install
  • generated app contract tests
  • generated app UI tests
• Ensure workflow installs Foundry and browser deps where required.

Implementation details

• Keep workflow lean and deterministic.
• Use cache keys based on lockfile.
• Provide documented knobs for projects that want to skip heavy tests.

Acceptance criteria

• New generated app can run CI without manual workflow authoring.
• Workflow passes for canonical generated job-board app.
• Workflow is documented in generated README and main repo docs.

[snissn]

Resolved by PR #36 (merged): emitted generated-app CI workflow template, scaffold docs, repo docs, and generation tests for workflow emission/knobs.