Summary

Add the ability to remove individual classes from an applied layer style
directly in the Classes panel. Removed classes are tracked as style
overrides, and Update/Reset actions (matching the LayerStylesPanel
pattern) let users save changes back to the style or revert.

Changes

• Add "x" button to style class badges in the Classes panel for removal
• Track removed style classes as styleOverrides so LayerStylesPanel
  shows "Customized" indicator
• Detect explicitly removed style classes (not just conflict-overridden)
  in overriddenStyleClasses
• Add Update and Reset actions (dropdown menu) mirroring LayerStylesPanel
• Wire up style update (propagates to all layers) and reset (reverts to
  original style) handlers with live collaboration broadcast

Test plan

• Select a layer with an applied style, open the Classes panel
• Remove a style class via "x" button — class shows strikethrough
• Confirm LayerStylesPanel shows "Customized" badge after removal
• Click "Update" — style definition updates, all layers using it reflect the change, overrides clear
• Remove a class again, then use "Reset" from dropdown — layer reverts to original style classes
• Verify collaboration broadcast works (style changes sync to other users)

Made with Cursor