chore: seal Design Vision v1 and monorepo scaffold

Archive the differentiated YuXinGu product docs, AI engineering system,
design contract, and Go/Vue scaffold. Next execution prioritizes Cece-parity
over early innovation (see .ai/product/STRATEGY.md).

Co-authored-by: Cursor <cursoragent@cursor.com>

.ai/design/platform/mini-program.md

@@ -0,0 +1,47 @@
+# Platform Contract — WeChat Mini Program
+
+Client: `apps/mini-program`.  
+Design language shared with H5; **implementation is native mini-program**, not Vue SFC reuse.
+
+Tokens: map `packages/ui` values into `app.wxss` / CSS variables supported by the base library — do not fork a second palette.
+
+---
+
+## MUST
+
+- Use Mini Program lifecycle (`onLoad` / `onShow` / …) and `wx` APIs.
+- Native navigation (`wx.navigateTo`, tabBar in `app.json`).
+- Components under `components/`; pages call `services/*` only (same idea as H5 sdk).
+- Support: share (`onShareAppMessage`), user authorization, payment flow when enabled.
+- Touch ≥ 44px; rpx spacing aligned to 4/8/12/16… scale.
+- Same IA tabs and domain copy rules as H5.
+- Paywall / Membership decisions still from API — never local unlock only.
+
+---
+
+## MUST NOT
+
+- `window` / `document` / DOM browser APIs.
+- Import Vue SFCs from `user-h5` as runtime.
+- Duplicate brand colors with new hex values.
+- Build UGC广场 or Consult marketplace in MVP.
+
+---
+
+## Mapping
+
+| H5 | Mini Program |
+|---|---|
+| Vue page | `pages/*` |
+| Pinia | global / store pattern approved in playbook |
+| `@yuxingu/sdk` | same package or thin `services` wrapper |
+| CSS modules | `wxss` + shared token sheet |
+
+---
+
+## Checklist
+
+- [ ] No browser-only APIs
+- [ ] Tokens mapped 1:1
+- [ ] Share / auth / pay paths considered
+- [ ] Catalog names reused