refactor: remove system-under-test lifecycle management, accept only a ready base url

[omermorad]

Decision

The caller owns application startup, readiness, service logs, and teardown. The action accepts sut.baseUrl and owns only the Playwright runner, test execution, reports, and portable artifacts.

Changes

• Remove Compose inputs, outputs, configuration support, lifecycle steps, CLI arguments, and result fields from action runtime.
• Reject the removed sut.composeFile setting. This is a breaking configuration change.
• Preserve runner validation, test failures, report publication, and result enforcement.
• Move the repository self-test SUT lifecycle into caller workflow steps, including always-run cleanup and a separate sut-logs artifact.
• Update recipes and diagrams to show ownership explicitly.

Verification

• All 36 offline regression checks passed, including caller gate and PR-comment failure handling.
• 3 real Playwright API tests passed in a cached runner against a temporary caller-started HTTP service. The action did not run Compose or contact staging.
• Syntax, YAML, local documentation links, and whitespace checks passed.

Companion

codotech/playwright-e2e-starter#1 uses @v0 and depends on a compatible release containing this implementation and demonstrates caller-owned Compose. Docker is still needed for runner/report images. API-secret forwarding remains outside this change. Nothing released or merged.

[github-actions]

E2E test report

Gate	✅ passed
Caller SUT	setup: success · cleanup: success · artifact: sut-logs
Tests	3 passed · 0 failed · 0 skipped · 3 total
Profile	pull-request
Projects	api, chromium
Tags	@smoke (any)
Runner	playwright-e2e-runner:e2e-88a155a50cf723b7063ef7f4d83f0e20943c861ddb5507080ae91f20c7082b3d (reused)
Results	e2e-results
Report image	playwright-e2e-report:36529759212-1 · e2e-report-image
Run	Open workflow run