chore(ci): don't run linter job for push

[swaldmann]

Currently linter is running twice for the same commit on main:

Have you...

• Added relevant entry to the change log?

[hyperspace-pr-bot]

Summary

The following content is AI-generated and provides a summary of the pull request:

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Title

Avoid duplicate Lint & Prettier CI runs on main pushes

Summary

Category: Chore

Updates the Lint & Prettier GitHub Actions workflow to stop running on direct pushes to main.

The workflow will continue to run for:

• pull_request events
• merge_group events

This avoids running the linter twice for the same commit after changes are merged, while keeping validation in place before code lands.

Have you...

• Added relevant entry to the change log?

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• 🔄 Regenerate and Update Summary
• ✏️ Insert as PR Description (deletes this comment)
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PR Bot Information

Version: 1.31.51

• LLM: gpt-5.5
• Summary Prompt: Default Prompt
• File Content Strategy: Full file content
• Event Trigger: pull_request.ready_for_review
• Correlation ID: 54024820-b831-11f1-8c4f-ff0363e5cee4
• Output Template: Repository PR Template