feat(admin): add posts CRUD sandbox and shared CRUD foundation

docs/.vitepress/config.mts

@@ -20,6 +20,7 @@ export default defineConfig({
           { text: "Getting Started", link: "/getting-started" },
           { text: "Architecture", link: "/architecture" },
           { text: "Better Auth Baseline", link: "/product-engineering/auth-baseline" },
+          { text: "CRUD Baseline", link: "/product-engineering/crud-baseline" },
           { text: "i18n Baseline", link: "/product-engineering/i18n-baseline" },
           { text: "RBAC And Permissions", link: "/product-engineering/rbac-permission-model" },
           { text: "Workflow", link: "/workflow" },

docs/architecture.md

@@ -6,6 +6,7 @@
 - `apps/admin`: admin app
 - `packages/db`: prisma + data access
 - `packages/content`: shared schemas and domain contracts
+- `packages/crud`: shared CRUD service patterns (validation, errors, audit hooks)
 - `packages/ui`: shared UI layer
 - `packages/i18n`: shared locale definitions and i18n helpers
 - `packages/config`: shared TS config

docs/product-engineering/crud-baseline.md

@@ -0,0 +1,33 @@
+# CRUD Baseline
+
+## Scope
+
+MVP0 now includes a shared CRUD foundation package: `@cms/crud`.
+
+Current baseline:
+
+- Shared service factory: `createCrudService`
+- Shared validation error type: `CrudValidationError`
+- Shared not-found error type: `CrudNotFoundError`
+- Shared mutation audit hook contract: `CrudAuditHook`
+- Shared mutation context contract (`actor`, `metadata`)
+
+## First Integration
+
+`@cms/db` `posts` now uses the shared CRUD foundation:
+
+- `listPosts`
+- `getPostById`
+- `createPost`
+- `updatePost`
+- `deletePost`
+- `registerPostCrudAuditHook`
+
+Validation for create/update is enforced by `@cms/content` schemas.
+
+The admin dashboard currently includes a temporary posts CRUD sandbox to validate this flow through a real app UI.
+
+## Notes
+
+- This is the base layer for future entities (pages, navigation, media, users, commissions).
+- Audit hook persistence/transport is intentionally left for later implementation work.