Add project scaffolding and infrastructure config

pnpm monorepo with shared packages, server, and UI workspaces.
Includes Docker multi-stage build, Postgres compose, and root TypeScript/Vitest config.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

docker-compose.yml

@@ -0,0 +1,25 @@
+services:
+  db:
+    image: postgres:17-alpine
+    environment:
+      POSTGRES_USER: paperclip
+      POSTGRES_PASSWORD: paperclip
+      POSTGRES_DB: paperclip
+    ports:
+      - "5432:5432"
+    volumes:
+      - pgdata:/var/lib/postgresql/data
+
+  server:
+    build: .
+    ports:
+      - "3100:3100"
+    environment:
+      DATABASE_URL: postgres://paperclip:paperclip@db:5432/paperclip
+      PORT: "3100"
+      SERVE_UI: "true"
+    depends_on:
+      - db
+
+volumes:
+  pgdata: