feat: add e2e tests for likes and fix like_count propagation in DTO mapping

- Write 3 e2e tests (TC-E2E-106-108): like/unlike flow, multi-user like, guest redirect
- Add get_like_count() and click_like() to PostDetailPage object
- Fix _map_to_dto in 5 use cases (create, get, list, publish, update) to include like_count
- Fix pre-existing mypy issues in page object (evaluate returns Any)
- Update FEATURE_LIKES.md with verified E2E status

app/application/use_cases/update_post.py

@@ -108,6 +108,7 @@ class UpdatePostUseCase:
             slug=post.slug.value,
             author_id=post.author_id,
             published=post.published,
+            like_count=post.like_count,
             tags=post.tags.copy(),
             created_at=post.created_at,
             updated_at=post.updated_at,