Editor: cursor not placed at tap location, and view jumps to top of note when dragging cursor via space bar (iOS)

Reported via support (Zendesk #11250033). User reports this has persisted across multiple updates - improved but not resolved.

### Expected
- Tapping a line in the editor places the cursor at the tapped location and keeps it there.
- Dragging the cursor by long-pressing the space bar moves the cursor smoothly without changing the scroll position.

### Observed
- After tapping a line, the cursor does not reliably stay where it was placed.
- When dragging the cursor via long-press on the space bar, the editor frequently jumps the scroll position to the top of the note.

### Reproduced
User reports this occurs frequently but not on every attempt (intermittent). Suggested steps to reproduce:

> 1. Open a note long enough to require vertical scrolling.
> 2. Tap on a line partway down the note to place the cursor.
> 3. Observe whether the cursor stays at the tapped location.
> 4. Long-press the space bar and drag to reposition the cursor.
> 5. Observe the editor jumping the scroll offset toward the top of the note.

The reporter provided screen recordings of both behaviors. These are not attached here, as they show the contents of the user's personal notes - they are available internally via the linked support ticket (Zendesk #11250033) for any Automattician who needs them.

**Possibly related historical work** (this symptom class was addressed before and may have regressed or only been partially fixed):
- #916 - Editor: Fixing iOS 14 Autoscroll Bug (view jumping to previous cursor location on tap)
- #973 / #982 - Fixing Text Selection (contentOffset jumping when tapping bottom lines; cursor-drag controllability)

Make|Model|iOS Version|App Version
-|-|-|-
Apple|iPhone 11 (red)|(unknown)|latest (4.55)

Start by reproducing the intermittent behavior with the listed steps on a long note, then review the historical work in #916, #973, and #982 for relevant editor behavior. Done means tapping reliably keeps the cursor at the tapped location and space-bar cursor dragging no longer moves the note's scroll position toward the top.

Written by the indexing model from the issue text.