feat(devcontainer): add enhanced Maven development environment with Java 21, Bun, and SSH support

- Add Docker Compose configuration for Maven + Java 21 development container
- Include SSH server support for remote development (Zed editor compatible)
- Install Bun package manager and opencode-ai for enhanced development workflow
- Provide Makefile with commands for build, up, down, restart, logs, shell, ssh, and clean
- Add .env.example template for configurable ports and paths
- Include .gitignore for Java/Maven artifacts and IDE files
- Configure USTC mirrors for faster package installation
- Support persistent volume mounting for root user configuration (.ssh, .m2 cache)

java-maven/vibe-enhance-version/compose.yml

@@ -0,0 +1,17 @@
+services:
+  maven-dev-env:
+    image: maven-java21-dev:3.9-ssh
+    build:
+      context: .
+      dockerfile: Containerfile
+    container_name: maven-devcontainer
+    hostname: maven-devcontainer
+    restart: always
+    ports:
+      - "${APP_PORT:-9090}:9090"
+      - "${SSH_PORT:-2322}:22"       # [新增] SSH 端口，宿主机通过 localhost:2222 连接
+    volumes:
+      - ${PROJECT_DIR:-/workspace}:/workspace
+      # 持久化 Root 用户配置（包含 .ssh, .m2 缓存, .config/zed 等）
+      - /workspace/devcontainer-vols/maven-devcontainer-root:/root
+