chore: acquire-core migration monorepo (legacy C + Spring Boot target skeleton)

TxCore/ECPG legacy 매입·정산 C 슬라이스(빌드검증) + Spring Boot 멀티모듈 골격(mvn test green) + MIGRATION.md 전환룰 + CI(boot 빌드).

boot/common-framework/pom.xml

@@ -0,0 +1,40 @@
+<?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.klaro.acquirecore</groupId>
+        <artifactId>acquire-core-boot</artifactId>
+        <version>0.0.1-SNAPSHOT</version>
+        <relativePath>../pom.xml</relativePath>
+    </parent>
+
+    <artifactId>common-framework</artifactId>
+    <packaging>jar</packaging>
+    <name>common-framework</name>
+    <description>TxCore 의 Spring 대체 공통 프레임워크 스타터 (라이브러리 jar)</description>
+
+    <dependencies>
+        <!-- 라이브러리이므로 web/실행 스타터 없이 코어 스타터만 -->
+        <dependency>
+            <groupId>org.springframework.boot</groupId>
+            <artifactId>spring-boot-starter</artifactId>
+        </dependency>
+    </dependencies>
+
+    <build>
+        <plugins>
+            <!-- 라이브러리 모듈은 실행 가능 jar 재패키징을 하지 않는다 -->
+            <plugin>
+                <groupId>org.springframework.boot</groupId>
+                <artifactId>spring-boot-maven-plugin</artifactId>
+                <configuration>
+                    <skip>true</skip>
+                </configuration>
+            </plugin>
+        </plugins>
+    </build>
+
+</project>