Cursor position wrong after pasting multi-line text in prompt input

[PrakharMNNIT]

Bug

After pasting multi-line text into the prompt input, the cursor lands in the middle of the pasted text instead of at the end.

Root Cause

document.execCommand('insertText') creates <div> block elements for multi-line text. getCursorPosition() doesn't count implicit newlines at block boundaries, but parseFromDOM() does. This cursor/text mismatch causes the cursor to be positioned incorrectly after the editor re-renders.

Steps to Reproduce

1. Copy multi-line text
2. Paste into the prompt input
3. Cursor lands in the middle instead of at the end

[github-actions]

This issue might be a duplicate of an existing issue. Please check:

• Desktop: Pasting newlines cause cursor **not** to be at end of pasted text #14429: "Desktop: Pasting newlines cause cursor not to be at end of pasted text" — describes the same bug (cursor position wrong after pasting multi-line text), and already has an associated PR (fix(desktop): count implicit newlines from block elements when pasting text #14428) with a fix.