refactor: consolidate Dockerfiles into single multi-stage build

- Create unified Dockerfile with multi-stage builds (base, server, ui targets)
- Centralize lib package.json COPYs in shared base stage (DRY)
- Add Claude CLI installation for Docker authentication support
- Remove duplicate apps/server/Dockerfile and apps/ui/Dockerfile
- Update docker-compose.yml to use target: parameter
- Add docker-compose.override.yml to .gitignore

Build commands:
  docker build --target server -t automaker-server .
  docker build --target ui -t automaker-ui .
  docker-compose build && docker-compose up -d

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

docker-compose.yml

@@ -13,7 +13,8 @@ services:
   ui:
     build:
       context: .
-      dockerfile: apps/ui/Dockerfile
+      dockerfile: Dockerfile
+      target: ui
     container_name: automaker-ui
     restart: unless-stopped
     ports:
@@ -25,7 +26,8 @@ services:
   server:
     build:
       context: .
-      dockerfile: apps/server/Dockerfile
+      dockerfile: Dockerfile
+      target: server
     container_name: automaker-server
     restart: unless-stopped
     ports: