Add category filtering to catalog

[benhalverson]

Summary

• add API-backed category chips to the home catalog page
• load the small catalog with a high product limit and filter/paginate client-side by URL-backed categoryId
• add category/product response typing and ProductList coverage for URL initialization, All reset, null-category products, and category fetch failure
• record the storefront/domain decisions from the planning session

Validation

• pnpm biome check src/pages/ProductList.tsx src/pages/ProductList.test.tsx src/interfaces/category.ts src/interfaces/index.ts src/interfaces/productResponse.ts
• pnpm test -- ProductList.test.tsx
• pnpm run build
• git diff --check

Notes

• Full pnpm run check still reports unrelated pre-existing formatting issues in ErrorBoundary.test.tsx, Product.test.tsx, Profile.test.tsx, and webauthn.test.ts.

[Copilot]

Pull request overview

This PR adds API-backed category filtering to the storefront catalog (ProductList), keeping the selected category in the URL (categoryId) while filtering and paginating client-side over a larger “small catalog” fetch. It also introduces category typing, tests around URL initialization/reset and failure handling, and adds ADR/context documentation capturing the storefront/domain decisions.

Changes:

• Fetch a larger product catalog once, fetch categories in parallel, and filter/paginate client-side based on URL categoryId.
• Add category/product response typing updates (including nullable/optional categoryId).
• Add Vitest coverage for category chips, URL sync/reset, uncategorized products, and category-fetch failure; add ADR/context docs.

Reviewed changes

Copilot reviewed 8 out of 8 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
src/pages/ProductList.tsx	Adds category chips driven by /categories, URL-backed categoryId, and client-side filtering/pagination over a larger catalog fetch.
src/pages/ProductList.test.tsx	New tests for URL initialization/reset, single-select category behavior, uncategorized products, and category fetch failure/toast behavior.
src/interfaces/productResponse.ts	Extends product typing with categoryId?: number | null.
src/interfaces/index.ts	Re-exports category interface.
src/interfaces/category.ts	Adds CategoryResponse typing for /categories.
docs/adr/0002-client-side-category-filtering-first.md	Records the client-side-first filtering decision and failure behavior expectations.
docs/adr/0001-keep-storefront-customer-facing.md	Captures the “storefront is customer-facing” decision.
CONTEXT.md	Adds shared vocabulary/definitions (storefront, category filter, uncategorized product, etc.).

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