ci: stop Node 26 from failing workflow

[ricellis]

PR summary

Add continue-on-error: true for Node 26 matrix job to prevent failing the entire workflow

PR Checklist

Please make sure that your PR fulfills the following requirements:

• The commit message follows the
  Angular Commit Message Guidelines.
• Tests for the changes have been added (for bug fixes / features)
• Docs have been added / updated (for bug fixes / features)

PR Type

• Bugfix
• Feature
• Code style update (formatting, local variables)
• Refactoring (no functional changes, no api changes)
• New tests
• Build/CI related changes
• Documentation content changes
• Other (please describe)

What is the current behavior?

Node 26 is not yet LTS but we test it as part of the matrix to get ahead of any issues.
It is not a required check, but if the job fails it causes the entire test workflow to fail, blocking merges.

What is the new behavior?

Add continue-on-error flag to the test job and get a value from ${{ matrix.node == '26' }} so it is true for Node 26 (i.e. the workflow can continue even if Node 26 fails).
It evaluates to false for Node 22 and 24 preserving the existing behaviour since we need both those checks to pass we can shortcut and stop work if one of them fails.

Does this PR introduce a breaking change?

• Yes
• No

Other information