Add Catalan (ca) translation agent skill guidelines

[ShubhamGondane]

Add locale-specific skill file for Catalan (ca) at .github/skills/airflow-translations/locales/ca.md, covering:

• Do-not-translate terms (Dag, XCom, Asset, Pool, etc.)
• Established glossary extracted from existing ca/*.json translation files
• Task/run state translations
• Catalan grammar rules: gender agreement, elision (d', l'), diacritics, plural forms (_one/_other), sentence case
• Action verb translations and usage examples
• Agent DO/DON'T instructions

closes: #61987

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Was generative AI tooling used to co-author this PR?

• Yes — Claude

Generated-by: Claude Sonnet 4.6 (Claude Code) following the guidelines

[boring-cyborg]

Awesome work, congrats on your first merged pull request! You are invited to check our Issue Tracker for additional contributions.

[github-actions]

Backport successfully created: v3-1-test

Note: As of Merging PRs targeted for Airflow 3.X
the committer who merges the PR is responsible for backporting the PRs that are bug fixes (generally speaking) to the maintenance branches.

In matter of doubt please ask in #release-management Slack channel.

Status	Branch	Result
✅	v3-1-test

[jscheffl]

@potiuk before just merging Language translations skills produced by AI... I had some important findings in German, also HU had review findings. Please have some native speaker reviewing before giving trust to AI too fast.

@ecodina @oscarhernandezrodriguez can you please make a post-merge review and potentially raise a correction PR?

[ecodina]

Thanks for tagging me @jscheffl

Some days ago I reviewed #62557

I wasn't aware we had another PR for Catalan AI skills. I'll test it next time I close the gap.

[potiuk]

@potiuk before just merging Language translations skills produced by AI... I had some important findings in German, also HU had review findings. Please have some native speaker reviewing before giving trust to AI too fast.

Oh yeah. I was too fast. Sorry.