Purpose:
1. Make the whole code base have unified "item" layout
2. Clarify our "list" styles: "flex-relaxed-list", "flex-divided-list"
3. Prepare to replace legacy "ui relaxed list"
* https://github.com/go-gitea/gitea/pull/37445#discussion_r3144458865
4. Prepare for refactoring the "pull merge box", it needs the
"flex-divided-list"
* related to "Refactor pull request view (*)" like #37451
5. Fix legacy abuses of "flex-list", e.g.: repo home sidebar
- add pr-review e2e test
- speed up most tests by logging in via POST to avoid the login form,
login form is still exercised in a dedicated test
- speed up most tests be removing post-test cleanup, unnecessary because
each repo is created with a unique name
- misc parallelization and api call reduction
- total suite runtime is about the same as before
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Co-authored-by: Claude (Opus 4.7) <noreply@anthropic.com>
Co-authored-by: wxiaoguang <wxiaoguang@gmail.com>