feat(channel): add mci-channel-wechat-personal adapter

- New module: mci-channel-wechat-personal
- Implements ChannelAdapter SPI for personal WeChat
- Calls Python channel-service pywechat HTTP APIs:
  - /v1/wechat-personal/login/start for initAccount QR code
  - /v1/wechat-personal/send/text and /send/image for sendMessage
- Configurable base URL via sino.channel.wechat-personal.base-url
- Added MockWebServer unit tests
- Wired module into backend parent and mci-server

backend/mci-channel-wechat-personal/pom.xml

@@ -0,0 +1,49 @@
+<?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.sino</groupId>
+        <artifactId>sino-mci-parent</artifactId>
+        <version>0.0.1-SNAPSHOT</version>
+    </parent>
+
+    <artifactId>mci-channel-wechat-personal</artifactId>
+    <name>mci-channel-wechat-personal</name>
+    <description>Personal WeChat channel adapter</description>
+
+    <dependencies>
+        <dependency>
+            <groupId>com.sino</groupId>
+            <artifactId>mci-channel-common</artifactId>
+        </dependency>
+        <dependency>
+            <groupId>org.springframework.boot</groupId>
+            <artifactId>spring-boot-starter-web</artifactId>
+        </dependency>
+        <dependency>
+            <groupId>com.fasterxml.jackson.core</groupId>
+            <artifactId>jackson-databind</artifactId>
+        </dependency>
+        <dependency>
+            <groupId>org.projectlombok</groupId>
+            <artifactId>lombok</artifactId>
+            <optional>true</optional>
+        </dependency>
+
+        <!-- Test -->
+        <dependency>
+            <groupId>org.springframework.boot</groupId>
+            <artifactId>spring-boot-starter-test</artifactId>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>com.squareup.okhttp3</groupId>
+            <artifactId>mockwebserver</artifactId>
+            <version>4.12.0</version>
+            <scope>test</scope>
+        </dependency>
+    </dependencies>
+</project>