Android: Hiding keyboard on empty block creates a stray empty block

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### Search first

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

### What Happened?

On the Android app (DB beta), when the cursor is in an empty block and the
"hide keyboard" button is pressed, the empty block gets saved/persisted.
Below it, a greyed-out bullet then appears indicating where new content can
be inserted.

This happens consistently when:
- Tapping the greyed-out bullet to create a new block, then
- Hiding the keyboard before typing anything.

An empty current edit should not result in an empty block being committed.

### Reproduce the Bug

1. Open a page or the journal on the Android app (DB beta).
2. Tap the greyed-out bullet (the placeholder for inserting new content)
so the cursor is in a new, empty block.
3. Without typing anything, hide the keyboard — either via the Logseq
"hide keyboard" button or via the standard Android back gesture/button.
4. Observe: the empty block is saved and a new greyed-out bullet appears
below it.

Note: Reproduces on both journal pages and regular pages.

### Expected Behavior

When the current block is empty (no content entered), hiding the keyboard
should discard/collapse the empty block rather than persisting it. No empty
block should be left behind.

### Screenshots

_No response_

### Files

_No response_

### Browser, Desktop or Mobile Platform Information

- Device: OnePlus 13
- OS: Android 16
- Platform: Android
- App version: 2.0.1-alpha+nightly.20260819 (DB beta)

### Additional Context

- The issue is reproducible every time the steps above are followed.
- Happens regardless of how the keyboard is hidden (Logseq "hide keyboard"
button or standard Android back gesture/button).
- Happens on both journal pages and regular pages.
- Related behavior: tapping the greyed-out bullet to start a new block and
then hiding the keyboard commits the empty block instead of discarding it.

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

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

Start by reproducing the issue on an Android page and journal page using both the Logseq hide-keyboard control and the standard Android back action. Trace the keyboard-dismissal path for a newly created empty block and verify that hiding the keyboard discards it without leaving a persisted block or a new greyed-out bullet.

Written by the indexing model from the issue text.