feat: scroll to first diff after apply completes

[uinstinct]

Description

Scroll to the first diff after apply completes irrespective of where the cursor is.

resolves CON-2190

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Checklist

• [] I've read the contributing guide
• [] The relevant docs, if any, have been updated or created
• [] The relevant tests, if any, have been updated or created

Screen recording or screenshot

feat.mp4

Tests

[ What tests were added or updated to ensure the changes work as expected? ]

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Summary by cubic

Scroll to the first diff after applying changes, centering the editor on that line regardless of the current cursor. Addresses Linear CON-2190.

• New Features
  • Capture the first changed line before clearing decorations and reveal it InCenter after apply.
  • Works even if the cursor was moved elsewhere during the apply.

[RomneyDa]

@uinstinct the goal is to stream to the first diff after apply finishes streaming, not after it is closed. The view should not move when diffs are accepted/rejected