Introduce a dedicated `/space/$namespace/$slug/compare` page that compares
two published skill versions GitHub-style: left file list + right unified
diff. Backend exposes `GET /versions/compare` returning structured diff
(computed via java-diff-utils) with per-file hunks, binary placeholder,
and truncation flags. Frontend uses two version selectors scoped to
PUBLISHED versions, a file search box, active-file highlighting, and
whitespace-preserving unified view. E2E covers the publish + rerelease
+ approve round trip; controller/domain tests cover happy path and
same-version rejection.
* chore(workflow): align local hooks and e2e guidance
* test(e2e): expand reusable api mock helpers
* test(skill): stabilize share button e2e assertions
* chore(test): add e2e make target and tune playwright workers
* test(web): expand e2e coverage and smoke suite
* test(e2e): migrate to real API flows and add request-based data builder
* ci(e2e): add PR workflow for real-service frontend e2e
* ci(e2e): install playwright chromium in PR workflow
* test(e2e): relax timeout and force single worker in CI
* test(e2e): stabilize not-found assertions and harden CI session bootstrap
* chore(agents): align tester role with web/e2e workflow
