fix(editor): hide empty container placeholder for inline styles

[DavidBabinec]

What changed

• Treat a non-empty nodeWrapperProps.style as authored styling for empty base.container nodes in the editor canvas.
• Added a regression test proving an inline-styled empty container keeps its root style but does not render the Empty container affordance.

Why

Class-styled empty containers already suppressed the placeholder, but inline-styled empty containers did not because ContainerEditor only checked mcClassName. That made the canvas behavior inconsistent between class and inline styling.

Impact

Authors can style empty containers inline for spacer/background/positioning use cases without the canvas showing the empty-state label over the authored element.

Verification

• bun test src/__tests__/base-modules-shared-render.editor.test.tsx (red before fix, green after)
• bun test
• bun run build
• bun run lint
• npx react-doctor@latest --verbose --scope changed --base origin/main