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>

apps/docs/standards/README.md

@@ -0,0 +1,22 @@
+# Deprecated as source of truth
+
+Engineering rules moved to the **AI Engineering System**:
+
+→ **[../../../.ai/](../../../.ai/)**
+
+| Old file | New location |
+|---|---|
+| 01-git | CONTRIBUTING.md + Trunk-Based note |
+| 02-go | `.ai/coding.md` + `.ai/tech-stack.md` |
+| 03-api | `.ai/api.md` |
+| 04-database | `.ai/database.md` |
+| 05-h5-vue | `.ai/ui.md` + `.ai/coding.md` |
+| 06-mini-program | `.ai/ui.md` + `.ai/architecture.md` |
+| 07-typescript | `.ai/coding.md` + `.ai/tech-stack.md` |
+| 08-testing | `.ai/testing.md` |
+| 09-cicd | `.ai/deployment.md` |
+| 10-ai-collab | `AGENTS.md` + `.ai/prompts/*` |
+| 11-security | `.ai/security.md` |
+| 12-docs | `.ai/definition-of-done.md` + `apps/docs` for PRD |
+
+Keep PRD / business docs: `apps/docs/prd-mvp.md`, `apps/docs/business-model.md`.