Add guinea-pig runner

[GuineaP]

Pull Request

Type of Change

• Add a new runner
• Fix or improve an existing runner
• Other (site, docs, tooling)

Summary

Adds guinea-pig, an original eight-frame monochrome guinea pig runner with a fast tiny-step patter animation.

中文使用者快速說明

這次新增一隻原創天竺鼠跑者，共 8 個黑色剪影影格。下載後解壓縮 guinea-pig-frames.zip，在 RunCat Neo 的自訂跑者編輯器依序匯入 frame 0 到 frame 7，並選擇 Template 或 monochrome 顯示模式，即可在淺色與深色選單列中使用。

Checklist for Adding a Runner

• I have read CONTRIBUTING.md and followed the steps described there.
• The runner is my original work, or I hold the rights to it, and I consent to its distribution under this repository's license (Apache-2.0).
• The runner does NOT contain third-party intellectual property.
• Files are placed at runners/guinea-pig/ as guinea-pig-frames.zip, metadata.json, and preview.png.
• All frames are PNG files named guinea-pig-frame-N.png, numbered from 0, exactly 36px tall, between 10px and 100px wide, and all share the same size.
• The zip contains only the frames — no .DS_Store, __MACOSX/, or ._* entries.
• metadata.json contains the correct author, displayName, type, and tags.
• preview.png is an animated PNG (APNG), 36px tall, at most 100px wide, and animates correctly.
• runners/manifest.json includes the new runner name and stays sorted alphabetically.