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docs/architecture.md

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+# Architecture
+
+## Monorepo Structure
+
+- `apps/web`: public app
+- `apps/admin`: admin app
+- `packages/db`: prisma + data access
+- `packages/content`: shared schemas and domain contracts
+- `packages/ui`: shared UI layer
+- `packages/config`: shared TS config
+
+## Design Principles
+
+- Shared contracts before feature implementation
+- RBAC and CRUD base as prerequisites for MVP1 feature work
+- Keep admin and public responsibilities clearly separated
+
+## Pending Documentation
+
+See documentation tasks in `TODO.md` under the Documentation track.