[johnnyhuy]

Part of #86
Closes #116

What changed: the plugin showcase page and cards now have component tests. ShowcasePage.test.tsx covers the initial render with item counts and category chips, category chip filtering, search filtering and the empty state. ShowcaseCard.test.tsx covers name, description, category label, the recommended badge, tag truncation to four, and the deep link target and label. No production code changed and nothing user-facing changed. This is a test-only slice.

How it was verified:

• mise run install - passed (Done with warnings in 2m 17s)
• mise run lint - passed (packages/backend 1 file, permission module 3 files, theme 1 file, plausible 8 files, packages/app 48 files, no errors)
• mise run test - passed: 5 suites passed, 1 skipped, 30 tests passed, 1 skipped. New tests: ShowcasePage renders every item with counts and chips, filters by category chip, filters by search term, shows the empty state. ShowcaseCard renders fields, shows the badge only when recommended, truncates tags to four, links the button to the template. Baseline on main was 22 passed, 1 skipped, so this adds 8 passing tests.
• mise run dev - frontend on localhost:3000 returned 200 and the backend responded on localhost:7007. Signed in as guest, opened /showcase, and the live page showed 14 items available with chips All (14), Code Templates (7), GitHub (3), Answer Engine (2), Platform (2), matching the counts the new tests assert.
• mise run build (Docker image) was not run. No backend code or packaging changed.

Proof:
Capture method (a) screenshot succeeded this run. Full page PNG of /showcase signed in as guest, saved at .tmp/proof/showcase-page.png on this branch: https://github.com/echohello-dev/backstage/blob/agent/issue-116-showcase-component-tests/.tmp/proof/showcase-page.png
Capture method (b) test output is pasted in the verification list above. The live snapshot from the same session listed Plugin Showcase, 14 items available and the first cards AI Hub Service and Answer Engine Worker with Recommended badges, matching the screenshot.

Known gaps and follow-ups:

• The parent epic Curate plugin showcase for templates GitHub and answer engine #86 stays open.
• Johnny: the Gumroad-style landing page look under Ship public showcase landing page with Gumroad-style direction #84 is still yours to direct. No design call was made here, and no landing page work was sliced this run.