Add Docker Compose project scaffold

Sets up the full monorepo structure with:
- Multi-stage Dockerfile (client-build + production stages)
- docker-compose.yml for production, docker-compose.dev.yml overlay for development
- Express server (port 3000) with pg pool, health route, and SPA static file serving
- React 18 + Vite client with react-router-dom v6, nav bar, and placeholder page components
- .env.example with PostgreSQL and app config
- Empty db/migrations/ directory for future migrations
- CLAUDE.md updated with development workflow commands

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

.claude/settings.local.json

@@ -0,0 +1,14 @@
+{
+  "permissions": {
+    "allow": [
+      "Bash(td --help)",
+      "Bash(td create:*)",
+      "Bash(EPIC=td-8064d2)",
+      "Bash(__NEW_LINE_51256bdd53dfa89e__ td:*)",
+      "Bash(td list:*)",
+      "Bash(git add:*)",
+      "Bash(git commit:*)",
+      "Bash(td start:*)"
+    ]
+  }
+}