chore: initial monorepo scaffold + WDS Phase 1+2 artifacts

- Nx 22.7 monorepo (pnpm 11.1, TypeScript 5.9, Node 24)
- apps/api: NestJS 11 (CJS conforme CODING-RULES.md PGD-DB-004)
- apps/web: React 19 + Vite 8 (ESM)
- libs/shared/api-interface: Zod contract base
- Docker Compose dev: Postgres 18, Valkey 8, MinIO, Mailpit
- WDS artifacts:
  - design-artifacts/A-Product-Brief/ (5 docs canônicos + 16 dialogs)
  - design-artifacts/B-Trigger-Map/ (hub + 4 personas + feature impact)
- Stack canon: STACK.md v2.2 + CODING-RULES.md v2.0 + brand.md
- AGENTS.md + README.md como entrada para devs/agentes

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

libs/shared/api-interface/src/lib/api-interface.ts

@@ -0,0 +1,3 @@
+export function apiInterface(): string {
+  return 'api-interface';
+}