[Feature] Make block handle works on mobile

[ziyak97]

Initial checklist

• I agree to follow the code of conduct
• I searched issues and discussions and couldn’t find anything (or linked relevant results below)

Affected packages and versions

"@milkdown/crepe": "^7.16.0",     "@milkdown/kit": "^7.16.0",     "@milkdown/react": "^7.16.0"

Link to runnable example

No response

Steps to reproduce

https://stackblitz.com/edit/github-ulgyjpjb?file=components%2FEditor.tsx

Added

      featureConfigs: {
        [Crepe.Feature.BlockEdit]: {
          blockHandle: {
            shouldShow: () => true,
          },
        },
      }

Expected behavior

With shouldShow: () => true configured for the blockHandle, the handle should consistently appear next to the currently active/focused block. Its position should be stable and predictable on both desktop and mobile devices.

Actual behavior

The blockHandle does not always show up next to the active block. It often appears on a previous block, and you need to hover over or interact with other blocks to get it to move to the correct location.
On mobile, this behavior is significantly worse. The handle's placement is very erratic, making it difficult to use for block-level operations.

Runtime

No response

OS

No response

Build and bundle tools

No response

[Saul-Mirone]

Block handle is not designed to work on mobile. Some extra works needed to make it works on mobile.

[ziyak97]

While it might not look ideal on mobile, I believe that shouldShow: () => true, if working as expected, should resolve some of the mobile usability issues.

Currently, the visibility of the block handle is determined by which block the user is hovering over; at least, that is my understanding.

My expectation was that shouldShow: () => true; would alter this behavior to always show the block handle on the currently focused block.

This would make it significantly easier to use on mobile, as it would eliminate the awkward mobile hover triggers.