Fix tab shortened path #2321

[RarityFan437]

Fixes the layout issue where tab titles failed to update when multiple tabs or splits were active. Replaced direct terminal parent fetching with an iterative tree traversal to correctly find the notebook page index.

Closes #2321

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RarityFan437

sem-ver: bugfix

[Davidy22]

Not strictly a part of your changes, but the comment immediately above the changed block does quite seem like a comment that will become less accurate with this change and probably should be changed too.