docs: clarify pixi vs hatch setup guidance in CONTRIBUTING

[axsseldz]

📝 Summary

Add a short tip in CONTRIBUTING.md guiding newcomers to choose pixi when they’re unfamiliar with both pixi and hatch.

🔍 Description of Changes

-Insert a tip callout explaining why pixi is the recommended default for new contributors.
-Include quick-start command sequences for both pixi and hatch to set up frontend and backend toolchains.

📋 Checklist

• I have read the contributor guidelines.
• For large changes, or changes that affect the public API: this change was discussed or approved through an issue, on Discord, or the community discussions (Please provide a link if applicable).
• Tests have been added for the changes made.
• Documentation has been updated where applicable, including docstrings for API changes.
• Pull request title is a good summary of the changes - it will be used in the release notes.

CC: @nojaf

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Project	Deployment	Actions	Updated (UTC)
marimo-docs	Ready	Preview, Comment	Feb 12, 2026 11:33pm

[axsseldz]

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