fix(report): align line numbers across contexts in diff view

[dberna2]

This PR fixes the diff view to display all line numbers on both sides, even when a line has no content.

Previously, only the existing line numbers were rendered (e.g., only 4 was shown on the right), which made the comparison harder to follow.

Before

After

Now, both contexts display the same number of lines, keeping the numbering aligned and making it easier to visually compare differences.

[sonarqubecloud]

Quality Gate failed

Failed conditions
C Maintainability Rating on New Code (required ≥ A)

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[dberna2]

Hi @rieckpil

I've noticed that the Sonar check is failing on this log request.
However, I haven't found anything in the new code that appears to violate the coding style or quality standards.
Do you know if any of the Sonar standards have changed recently, or if there's any other reason why the scan might be failing?

[rieckpil]

thanks for this convenient fix, @dberna2! I haven't had a detailed look into the Sonar settings yet, so I'm happy to merge and adopt later.