test(components): backfill tutorial surface coverage

[bntvllnt]

Summary

• Added Vitest coverage for five previously untested tutorial/content components: category-filter, content-intro, table-of-contents-panel, tutorial-filters, and tutorial-intro-content.
• Covered rendering, callback payloads, progress states, keyboard/backdrop interactions, markdown rendering, category sorting/deduping, and route-aware selected-category behavior.
• Kept the batch test-only with no component source changes.

Part of #231

Validation

• pnpm -F @vllnt/ui exec vitest run src/components/category-filter/category-filter.test.tsx src/components/content-intro/content-intro.test.tsx src/components/table-of-contents-panel/table-of-contents-panel.test.tsx src/components/tutorial-filters/tutorial-filters.test.tsx src/components/tutorial-intro-content/tutorial-intro-content.test.tsx PASS (23 tests)
• pnpm -F @vllnt/ui exec eslint src/components/category-filter/category-filter.test.tsx src/components/content-intro/content-intro.test.tsx src/components/table-of-contents-panel/table-of-contents-panel.test.tsx src/components/tutorial-filters/tutorial-filters.test.tsx src/components/tutorial-intro-content/tutorial-intro-content.test.tsx PASS
• pnpm -F @vllnt/ui lint PASS
• pnpm -F @vllnt/ui exec tsc --noEmit --project tsconfig.build.json PASS
• pnpm build PASS
• pnpm test:once PASS (221 files, 1238 tests)
• git diff --check PASS

Notes: pnpm build emitted the existing Next.js multiple-lockfile warning for this nested worktree. pnpm test:once emitted existing jsdom navigation, duplicate-key, and Radix dialog description warnings while passing.

Design Deviations

None.

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Project	Deployment	Actions	Updated (UTC)
storybook	Ready	Preview, Comment	May 12, 2026 6:57pm
ui.vllnt.ai	Ready	Preview, Comment	May 12, 2026 6:57pm