refactor: move docker-compose files to deploy/ directory structure

Reorganize Docker configuration into environment-specific directories:
- deploy/dev/: Development with hot reload and source mounting
- deploy/test/: Ephemeral testing with branch isolation and dynamic ports
- deploy/prod/: Production with resource limits, logging, and restart policy

Key improvements in test compose:
- Dynamic ports (no fixed 3000/8484) for parallel test runs
- Branch-isolated container/network names via TEST_INSTANCE_ID
- service_healthy condition instead of service_started
- Increased retry counts for stability

deploy/dev/.env.example

@@ -0,0 +1,3 @@
+PORT=3000
+GRIST_MCP_TOKEN=your-token-here
+CONFIG_PATH=/app/config.yaml