feat(im): 添加即时通讯功能模块

- 添加了 IM API 接口定义，包含登录、消息、群组、好友等接口
- 实现了 ImSDK 核心功能，支持发送各类消息和管理会话
- 集成了 WebSocket 连接管理和自动重连机制
- 添加了本地联系人缓存并优化对话标题显示逻辑
- 实现了 HarmonyOS 平台 HTTP 客户端基础功能

docs/PLATFORM_OVERVIEW.md

@@ -83,7 +83,12 @@
 | 平台 | Registry | 命令 |
 |------|----------|------|
 | npm (RN SDK / Vue3 SDK) | https://nexus.xuqinmin.com/repository/npm-hosted/ | `npm publish` |
-| Android Maven | https://nexus.xuqinmin.com/repository/android-hosted/ | `./gradlew publish` |
+| npm download | https://nexus.xuqinmin.com/repository/npm/ | client consumption |
+| Android Maven upload | https://nexus.xuqinmin.com/repository/android-hosted/ | `./gradlew publish` |
+| Android Maven download | https://nexus.xuqinmin.com/repository/android/ | client consumption |
+| Java Maven upload (release) | https://nexus.xuqinmin.com/repository/maven-releases/ | `mvn deploy` |
+| Java Maven upload (snapshot) | https://nexus.xuqinmin.com/repository/maven-snapshots/ | `mvn deploy` |
+| Java Maven download | https://nexus.xuqinmin.com/repository/maven-public/ | client consumption |
 | iOS SPM | Git Tag | `git tag x.y.z && git push origin x.y.z` |
 | iOS CocoaPods | https://xuqinmin.com/xuqinmin12/xuqm-specs | `pod repo push xuqm-specs XuqmSDK.podspec` |
 | HarmonyOS | ohpm (OpenHarmony Package Manager) | `ohpm publish` |

im-sdk/pom.xml

@@ -0,0 +1,43 @@
+<?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 https://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+
+    <parent>
+        <groupId>com.xuqm</groupId>
+        <artifactId>xuqmgroup-server-parent</artifactId>
+        <version>0.1.0-SNAPSHOT</version>
+        <relativePath>../pom.xml</relativePath>
+    </parent>
+
+    <artifactId>im-sdk</artifactId>
+    <name>im-sdk</name>
+    <description>Java SDK for XuqmGroup IM service and REST APIs</description>
+
+    <dependencies>
+        <dependency>
+            <groupId>com.xuqm</groupId>
+            <artifactId>common</artifactId>
+        </dependency>
+        <dependency>
+            <groupId>com.fasterxml.jackson.core</groupId>
+            <artifactId>jackson-databind</artifactId>
+        </dependency>
+        <dependency>
+            <groupId>com.fasterxml.jackson.datatype</groupId>
+            <artifactId>jackson-datatype-jsr310</artifactId>
+        </dependency>
+    </dependencies>
+
+    <distributionManagement>
+        <repository>
+            <id>xuqm-maven-releases</id>
+            <url>https://nexus.xuqinmin.com/repository/maven-releases/</url>
+        </repository>
+        <snapshotRepository>
+            <id>xuqm-maven-snapshots</id>
+            <url>https://nexus.xuqinmin.com/repository/maven-snapshots/</url>
+        </snapshotRepository>
+    </distributionManagement>
+</project>

im-service/src/main/java/com/xuqm/im/controller/AccountController.java

@@ -0,0 +1,50 @@
+package com.xuqm.im.controller;
+
+import com.xuqm.common.exception.BusinessException;
+import com.xuqm.common.model.ApiResponse;
+import com.xuqm.im.entity.ImAccountEntity;
+import com.xuqm.im.service.ImAccountService;
+import org.springframework.http.ResponseEntity;
+import org.springframework.security.core.annotation.AuthenticationPrincipal;
+import org.springframework.web.bind.annotation.GetMapping;
+import org.springframework.web.bind.annotation.PathVariable;
+import org.springframework.web.bind.annotation.PutMapping;
+import org.springframework.web.bind.annotation.RequestMapping;
+import org.springframework.web.bind.annotation.RequestParam;
+import org.springframework.web.bind.annotation.RestController;
+
+import java.util.Objects;
+
+@RestController
+@RequestMapping("/api/im/accounts")
+public class AccountController {
+
+    private final ImAccountService accountService;
+
+    public AccountController(ImAccountService accountService) {
+        this.accountService = accountService;
+    }
+
+    @GetMapping("/{userId}")
+    public ResponseEntity<ApiResponse<ImAccountEntity>> get(
+            @AuthenticationPrincipal String currentUserId,
+            @RequestParam String appId,
+            @PathVariable String userId) {
+        return ResponseEntity.ok(ApiResponse.success(accountService.getAccount(appId, userId)));
+    }
+
+    @PutMapping("/{userId}")
+    public ResponseEntity<ApiResponse<ImAccountEntity>> update(
+            @AuthenticationPrincipal String currentUserId,
+            @RequestParam String appId,
+            @PathVariable String userId,
+            @RequestParam(required = false) String nickname,
+            @RequestParam(required = false) String avatar,
+            @RequestParam(required = false) ImAccountEntity.Gender gender) {
+        if (!Objects.equals(currentUserId, userId)) {
+            throw new BusinessException(403, "Only the account owner can update profile");
+        }
+        return ResponseEntity.ok(ApiResponse.success(
+                accountService.updateAccount(appId, userId, nickname, avatar, gender)));
+    }
+}

pom.xml

@@ -15,6 +15,7 @@
         <module>common</module>
         <module>tenant-service</module>
         <module>im-service</module>
+        <module>im-sdk</module>
         <module>push-service</module>
         <module>update-service</module>
         <module>demo-service</module>