서버 프로젝트 초기화

- Language: Kotlin
- Framework: SpringBoot
- DB: MemoryDB(H2) 이후 변동 가능
- Security: Oauth2

This is a project initialization task, not a specific code change. Start by examining the repository structure to see what exists. Look for existing Spring Boot configuration, build files (like build.gradle.kts or pom.xml), and any OAuth2 or H2 setup. The goal is to set up a basic server with the listed technologies. 'Done' means a runnable Spring Boot application with H2 database connectivity and OAuth2 security skeleton configured.

索引モデルが issue の本文から書いたものです。