Add Bubu Codebrew Bear pet

[xxhh0822]

Summary

• Add 布布 / Bubu as an original Codex Pets v2 companion.
• Add a transparent 192×208 preview and the validated 1536×2288 v2 spritesheet.
• Append the pet to the Chinese and English indexes without reordering existing entries.
• Add the GitHub Pages catalog entry under the existing Original category.

Source and authorship

• Character/work source: original coding-bear workstation concept supplied by the contributor; this is not based on a third-party character, person, or brand.
• Asset creator and GitHub user: @xxhh0822.
• Creation method: original AI-assisted artwork; no third-party source pixels were copied.
• Rights confirmation: I confirm that I own the necessary rights to submit and license the contributed original material.

License

• Original pet assets are contributed under CC BY-NC-SA 4.0 as required by this repository.
• The pet directory includes LICENSE.md with attribution, source, permitted use, and third-party rights boundaries.

Validation

• Directory name matches pet.json ID: original-bubu-codebrew-bear
• pet.json is valid JSON and uses spriteVersionNumber: 2
• spritesheetPath resolves to spritesheet.webp
• Spritesheet is transparent 1536×2288, 8×11, and atlas validation passes with no errors or warnings
• preview.webp is transparent 192×208 and clearly shows the pet
• Chinese and English README entries are appended at the end
• script.js contains the Original-category entry and passes node --check
• The pet directory contains exactly the four required files
• No unrelated files or deletions are included