docs(product): add cms feature topics, package catalog, and inspiration notes

docs/product-engineering/package-catalog.md

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+# Package Catalog And Decision Notes
+
+## Purpose
+
+Track package decisions in one place:
+
+- what is already used
+- why it is used
+- when to keep/remove/replace
+- which packages are candidates for later MVPs
+
+This file is decision support, not a lockfile replacement.
+
+## Current Core Stack (Used Now)
+
+### Runtime and App Foundation
+
+- `bun`:
+  workspace package manager + runtime for scripts and local dev.
+- `next` + `react` + `react-dom`:
+  app framework for `admin` and `web`.
+- `typescript`:
+  typed contracts across apps/packages.
+
+### Data and Validation
+
+- `prisma` + `@prisma/client` + `pg` + `@prisma/adapter-pg`:
+  DB schema/migrations + typed DB access on PostgreSQL.
+- `zod`:
+  shared runtime validation for domain schemas and CRUD inputs.
+
+### Auth, State, Data Fetching
+
+- `better-auth`:
+  admin auth/session + role metadata baseline.
+- `zustand`:
+  lightweight client state (e.g. locale/UI state).
+- `@tanstack/react-query`:
+  async state/query cache patterns for admin/public app data fetching.
+- `@tanstack/react-form` and `@tanstack/react-table`:
+  form/table primitives in admin workflows.
+
+### UI and Styling
+
+- `tailwindcss` + `@tailwindcss/postcss`:
+  utility-first styling baseline.
+- `class-variance-authority`, `clsx`, `tailwind-merge`:
+  component variant + class composition in `@cms/ui`.
+
+### Testing and Quality
+
+- `vitest`, `@testing-library/react`, `@testing-library/jest-dom`, `@testing-library/user-event`, `msw`, `jsdom`:
+  unit/integration tests + UI interaction + API mocking.
+- `@playwright/test`:
+  end-to-end tests.
+- `@biomejs/biome`:
+  lint/format/check baseline.
+- `turbo`:
+  monorepo task orchestration.
+
+### Docs and Release Governance
+
+- `vitepress`:
+  docs site.
+- `conventional-changelog-cli`:
+  changelog generation from conventional commits.
+- `@commitlint/cli` + `@commitlint/config-conventional`:
+  commit message schema enforcement.
+
+## Media and Color Processing Notes
+
+### Why `sharp` is typically the default choice
+
+`sharp` is usually the best baseline for server-side image processing because:
+
+- strong performance and memory behavior
+- reliable resize/crop/format conversion pipeline
+- robust support for production workloads
+- good integration in Node/Bun server contexts
+
+Use cases for this CMS:
+
+- generate artwork renditions (thumb/card/full/custom)
+- normalize uploads and output formats
+- create banner/promo safe-size outputs
+- optional watermark compositing pipeline
+
+### Color extraction package options
+
+1. `node-vibrant`
+- Best for: quick dominant palette extraction for UI accents and tagging.
+- Tradeoff: less control over advanced color science.
+
+2. `colorthief`
+- Best for: simple dominant-color extraction with minimal setup.
+- Tradeoff: more limited output and tuning compared to richer libraries.
+
+3. `culori` / `chroma-js` (supporting libs, often combined with extractor)
+- Best for: color manipulation, conversion, contrast checks, palette normalization.
+- Tradeoff: not a full image extractor by itself.
+
+Recommended approach:
+
+- MVP2 start with `sharp` + `node-vibrant` + `culori`
+- keep extraction pipeline behind an internal adapter so replacement is easy
+
+## Candidate Packages For Later (Not Installed Yet)
+
+### File Upload and Storage Abstraction
+
+- `@aws-sdk/client-s3` (+ presign utilities):
+  for S3/R2/object storage adapters and signed upload/download flows.
+- `uploadthing` or custom presigned-upload implementation:
+  faster admin upload UX with secure direct-to-storage path.
+
+### Rich Text / Page Builder
+
+- `tiptap`:
+  rich editorial experience for pages/news.
+- `@dnd-kit/core`:
+  drag-and-drop block ordering/page-builder interactions.
+
+### Media Pipelines / Jobs
+
+- `bullmq` + `ioredis`:
+  background job queue for heavy media transforms (watermark/video/etc).
+
+### Commissions and CRM Extensions
+
+- `@tanstack/react-virtual`:
+  large admin tables (requests/customers) without rendering bottlenecks.
+
+### Observability / Reliability
+
+- `@sentry/nextjs`:
+  app error monitoring.
+- `pino`:
+  structured logs for services/workflows.
+
+## Add/Remove Decision Rules
+
+When adding a package, document:
+
+1. problem it solves
+2. why existing stack is insufficient
+3. expected maintenance/runtime cost
+4. fallback/exit plan
+
+When removing/replacing:
+
+1. list impacted modules
+2. verify tests and migration path
+3. update this catalog and related ADR/docs