fix(core): Replace deprecated 'application' actor value with 'app' in Linear OAuth

[adriencohen]

Summary

Linear has deprecated the actor=application parameter, which causes OAuth authentication to fail with a 503 error.
This PR updates the integration to use the new actor=app parameter.

Temporary workaround:

If you're currently blocked, copy the OAuth URL opened by n8n, replace application with app, and continue the flow. It will work as expected.

Linear documentation

Note, we previously supported a similar actor=application as a mode – this was deprecated in favor of the behavior in actor=app. If your app already uses this option then you can continue to do so.

Related Linear tickets, Github issues, and Community forum posts

• https://community.n8n.io/t/linear-oauth2-api-fails-with-503-error/135227
• closes Linear OAuth2 API fails with 503 error #19599

Review / Merge checklist

• PR title and summary are descriptive. (conventions)
• Docs updated or follow-up ticket created.
• Tests included.
• PR Labeled with release/backport (if the PR is an urgent fix that needs to be backported)

[CLAassistant]

All committers have signed the CLA.

[cubic-dev-ai]

No issues found across 1 file

[n8n-assistant]

Hey @adriencohen,

Thank you for your contribution. We appreciate the time and effort you’ve taken to submit this pull request.

Before we can proceed, please ensure the following:
• Tests are included for any new functionality, logic changes or bug fixes.
• The PR aligns with our contribution guidelines.

Regarding new nodes:
We no longer accept new nodes directly into the core codebase. Instead, we encourage contributors to follow our Community Node Submission Guide to publish nodes independently.

If your node integrates with an AI service that you own or represent, please email nodes@n8n.io and we will be happy to discuss the best approach.

About review timelines:
This PR has been added to our internal tracker as "GHC-5127". While we plan to review it, we are currently unable to provide an exact timeframe. Our goal is to begin reviews within a month, but this may change depending on team priorities. We will reach out when the review begins.

Thank you again for contributing to n8n.