refactor: 对齐后端样例工程规范

backend/api/etc/platform.env.example

@@ -0,0 +1,4 @@
+BSM_Workspace=default
+BSM_RuntimeMode=dev
+BSM_Prefix=./etc
+BSM_JwtSecretKey=change-me-to-a-random-string

backend/api/etc/platform_dev.yaml

@@ -0,0 +1,12 @@
+Service: platform
+Port: 12426
+
+Databases:
+  Driver: postgres
+  Source:
+    - host=127.0.0.1 user=postgres password=change-me dbname=agent_dev port=5432 sslmode=disable TimeZone=Asia/Shanghai
+
+# Redis 仅用于缓存、会话、限流和 Streams；首期外部事件适配使用 Mock。
+Cache: redis://default:change-me@127.0.0.1:6379/0
+OnMicroService: false
+SecretKey: change-me-to-a-random-string