Snapshots for Reddit, GitLab, etc.

Before public launch, I want HAR snapshots ready for Reddit and GitLab, maybe others, so that it's easy for new contributors to make idiomatic contributions.

Start by locating any existing HAR snapshots and the repository conventions for storing or loading them. Confirm which Reddit and GitLab flows need coverage before adding fixtures, and define done as reproducible snapshots for both services that new contributors can use for idiomatic changes.

索引モデルが issue の本文から書いたものです。