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

deploy/dev/docker-compose.yml

@@ -0,0 +1,19 @@
+# Development environment - hot reload, persistent data
+services:
+  grist-mcp:
+    build:
+      context: ../..
+      dockerfile: Dockerfile
+    ports:
+      - "${PORT:-3000}:3000"
+    volumes:
+      - ../../src:/app/src:ro
+      - ../../config.yaml:/app/config.yaml:ro
+    env_file:
+      - .env
+    healthcheck:
+      test: ["CMD", "python", "-c", "import urllib.request; urllib.request.urlopen('http://localhost:3000/health')"]
+      interval: 30s
+      timeout: 10s
+      retries: 3
+      start_period: 60s