[CHORE] Set CI for validating the built files (`dist/`)

[daisuke-sato-datalabs]

Outline（概要）

Set CI for validating the built files (dist/).

Background（背景・経緯）

We need to manually track the updates of the files above with git for a reason:
#5 (comment)

So, it is better to verify that the files are built from the latest version of the source codes.

Spec（仕様）

Before merging PRs, run the following verification:

• Build from the updated source codes (yarn build)
• Take diff with the stored built files
• If there are diff, block the merge

Deadline（期限）

Reference（参考）