添加 Dex 认证配置和初始化脚本，创建 .env 示例文件，更新 docker-compose 配置以支持 OIDC 认证

config/dex.config.yml

@@ -0,0 +1,29 @@
+issuer: http://localhost:5556
+
+storage:
+  type: sqlite3
+  config:
+    file: /var/lib/dex/dex.db
+
+web:
+  http: 0.0.0.0:5556
+  allowedOrigins: ["*"]
+
+logger:
+  level: debug
+  format: text
+
+enablePasswordDB: true
+
+staticClients:
+- id: excalidraw
+  redirectURIs:
+  - http://localhost:3002/auth/oidc/callback
+  name: Excalidraw
+  secret: ${OIDC_CLIENT_SECRET:-excalidraw-secret}
+
+staticPasswords:
+- email: ${ADMIN_EMAIL:-admin@example.com}
+  hash: ${ADMIN_PASSWORD_HASH}
+  username: ${ADMIN_USERNAME:-admin}
+  userID: "admin-001"