feat(product-center): implement Figma-designed UI, upload module, and website tests

- Redesign website homepage & product-center per Figma (fonts, logos, hero/footer/customer cases)
- Add API upload module (multer) with static serving for uploads/public assets
- Add OriginGood.delisted flag and SDS request retry logic
- Add admin ImageUpload component and goods import/upload flows
- Add vitest suite for website components and composables (32 tests)
- Add skills, docs, plans and PRODUCT.md

plans/fix/product-external-id-fix.md

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+# Product External ID Fix Implementation Plan
+
+> **For agentic workers:** REQUIRED SUB-SKILL: Use executing-plans to implement this plan task-by-task. Steps use checkbox (`- [ ]`) syntax for tracking.
+
+**Goal:** Make the public goods API return the SDS/InkPOD product ID as `id`, so product-card links target the correct InkPOD detail page.
+
+**Architecture:** Keep the local `goods.good_id` as the database identity used by admin and relations. At the public API serialization boundary, map `originGood.sdsGoodId` to the existing response `id` field; the website can continue consuming `product.id` without a second identifier.
+
+**Tech Stack:** NestJS, Prisma, Jest, Nuxt/Vue
+
+---
+
+### Task 1: Lock the public API ID contract
+
+**Files:**
+- Modify: `apps/api/src/public/public.service.spec.ts`
+
+- [x] Add an assertion that a listed public product has `id` equal to the seeded `OriginGood.sdsGoodId`, not the local `Good.id`.
+- [x] Run the focused API test and confirm it fails because the service currently returns `good.id`.
+
+### Task 2: Return the SDS product ID
+
+**Files:**
+- Modify: `apps/api/src/public/public.service.ts`
+
+- [x] Include `sdsGoodId` in the serializer's `originGood` type.
+- [x] Return `good.originGood.sdsGoodId` as `PublicGoodDto.id`.
+- [x] Run the focused API test and confirm it passes.
+
+### Task 3: Verify consumers and document the contract
+
+**Files:**
+- Modify: `docs/references/product-center.md`
+- Modify: `docs/references/structs.md`
+
+- [x] Document that public product `id` is the SDS/InkPOD external product ID.
+- [x] Run API public-service tests, website tests, and the website build.
+- [ ] Verify the running public endpoint returns `126673` for `200g纯棉T恤KRTM001` when local services are available. (The API was not listening on port 3001 during verification.)