test-case-implement

Implements a test case (TC-XXX) as an automated end-to-end test: runs the E2E test skill recorded in docs/architecture/stack.md (vaadin-e2e-test, playwright-e2e-test) with the journey, so every Flow row of the test case becomes a test step and every Validation item an assertion against the running application. Applies the rules of /use-case-test: the test case is the oracle, a test that disagrees with the code stays failing, an existing journey test is reconciled rather than duplicated. Use when the user asks to "implement TC-001", "automate TC-001", "write the end-to-end test for this test case", "turn the journey into a test", or mentions an automated test for a TC-* document in a project that combines layer plugins (aiup-vaadin, aiup-playwright). With a combined stack plugin (aiup-vaadin-jooq, aiup-angular-jpa, aiup-blazor-dotnet, aiup-nestjs-nextjs), use its /playwright-test TC-XXX. Writes test code; the TC-*.md document itself is /test-case.