Store .png in .png files instead of converting them to .jpeg files

[a1fredbao]

PNG have transparent pixels and converting them to jpeg files may cause loss of such pixels.

Therefore, I think we should store .png in .png files instead of converting them to .jpeg files.

Maybe I'll make a PR some day.

[langningchen]

If you're planning to work on it, please let me know. Otherwise, I'll use Codex to fix it right away.

[a1fredbao]

If you're planning to work on it, please let me know. Otherwise, I'll use Codex to fix it right away.

Yeah might as well just let codex do the job, no big deal.

[openai-code-agent]

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[anthropic-code-agent]

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