feat: add saber-theme-paper

[geekplux]

Summary

What kind of change does this PR introduce? (check at least one)

• [ ] Bugfix
• [ ] Feature
• [ ] Code style update
• [ ] Refactor
• [ ] Docs
• [ ] Build-related changes
• [x] Other, please describe: add a saber theme

If changing the UI/CSS related code, please provide the before/after screenshot:

Does this PR introduce a breaking change? (check one)

• [ ] Yes
• [x] No

If yes, please describe the impact and migration path for existing applications:

The PR fulfills these requirements:

• [ ] Briefly describing what this PR does in the title in Angular Commit Message Conventions, e.g. fix: rebuild when a page is added

To avoid wasting your time, it's best to open a feature request issue first and wait for approval before working on it.

Other information:

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