Support `spx-property-name` input type in InputHelper (in-place modify via property selector)

[cn0809]

Background

xgolsw recently introduced a new input slot accept type: spx-property-name. see: goplus/xgolsw#281

In the current editor behavior, the hover Modify action would be shown for such slots, but InputHelper does not provide a handler for this type, so in-place editing is not supported (Value not supported fallback).

Goal

Add full InputHelper support for accept.type = spx-property-name, so users can modify the value through a selector-based in-place editor.

Proposed implementation path

• Add a new input type handler for spx-property-name in the SPX-specific input helper provider.
• Resolve code owner scope (stage/sprite) from editor context using codePath (same approach as existing owner/context resolution logic).
• Fetch candidate properties by calling language server command getProperties with the resolved owner context.
• Render in-place editor as a selector (dropdown/select component) populated with fetched properties.
• Commit selected property name back to the slot as in-place input value and update code through existing InputHelper flow.