feat: App 后台 Phase 1 Maven 治理 + Docker 部署

- 创建 xiaoqu-app-parent 统一父 POM，管理 4 个 App 模块依赖版本
- 统一 fastjson(1.2.83)、druid(1.2.27)、jedis(3.1.0) 等版本
- 子模块 POM 改造：继承父 POM，删除硬编码版本号
- 添加 Docker 部署方案（complex + mall 双容器）
- 添加 ARCHITECTURE.md 架构文档（三套 DAO 层、冻结规范、新项目规范）
- 关联需求：REQ-20260421-0011

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

backend/xiaoqu-public/pom.xml

@@ -0,0 +1,33 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0"
+         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <parent>
+        <groupId>me.iiv.xiaoqu</groupId>
+        <artifactId>xiaoqu-app-parent</artifactId>
+        <version>1.0-SNAPSHOT</version>
+        <relativePath>../xiaoqu-app-parent/pom.xml</relativePath>
+    </parent>
+
+    <modelVersion>4.0.0</modelVersion>
+    <artifactId>xiaoqu-public</artifactId>
+
+    <dependencies>
+        <dependency>
+            <groupId>com.alibaba</groupId>
+            <artifactId>fastjson</artifactId>
+        </dependency>
+        <dependency>
+			<groupId>cn.hutool</groupId>
+			<artifactId>hutool-all</artifactId>
+		</dependency>
+		<dependency>
+			<groupId>io.swagger</groupId>
+			<artifactId>swagger-models</artifactId>
+		</dependency>
+		<dependency>
+			<groupId>org.projectlombok</groupId>
+			<artifactId>lombok</artifactId>
+		</dependency>
+    </dependencies>
+</project>