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>

pnpm-workspace.yaml

@@ -0,0 +1,4 @@
+packages:
+  - packages/*
+  - server
+  - ui