add Gradle test workflow

[cfcromn]

작업 내용

• GitHub Actions CI workflow 추가
• JDK 21 + Gradle cache 설정
• push / pull_request 시 ./gradlew test 실행
• Bug/Todo issue template 추가
• PR template 추가

검증

• ./gradlew test

Close #1

[gemini-code-assist]

Code Review

This pull request introduces GitHub issue templates for bugs and tasks, along with a pull request template. The review feedback correctly identifies critical schema issues in the YAML templates, such as missing required 'id' fields for 'textarea' inputs and the need to format the 'labels' field as an array to avoid parsing errors. Additionally, it suggests adding a placeholder for the issue number in the pull request template to improve clarity.

Important

The consumer version of Gemini Code Assist on GitHub is being sunset. Starting June 18, 2026, new organization installations will be blocked, and all code review activity will officially cease on July 17, 2026.
For more details on the timeline and next steps, please review the Help Documentation.