Cursor jumps to page title when first/last block is deleted via Backspace

@tiensonqin is already working on this.

Since Sep 17, 2026.

### Search first

- [x] I searched and no similar issues were found

### What Happened?

When a page is empty and I click into the first (empty) block and press Backspace, the cursor jumps into the page title.

The same happens when deleting the last block of a page as a whole (i.e. not while editing it): after the block is removed, the cursor suddenly sits in the page title.

This also occurs in the journal: deleting the last block of a journal page puts the cursor into the date title.

### Reproduce the Bug

1. Create/open an empty page (or a journal page with a single block).
2. Click into the first empty block (or select the last block of the page as a whole, without editing it).
3. Press Backspace.

**Observed:** The cursor jumps into the page title (in the journal: into the date title).

### Expected Behavior

The cursor should remain in the block editing area (e.g. in the first/last remaining block) instead of moving into the page title.

### Screenshots

_No response_

### Files

_No response_

### Browser, Desktop or Mobile Platform Information

- Platform: Linux Desktop
- Version: 2.0.1-alpha+nightly.20260916 (DB beta)

### Additional Context

This may be an oversight in the fix of issue #1094

### Are you willing to submit a PR? If you know how to fix the bug.

- [ ] I'm willing to submit a PR (Thank you!)