Fix ColumnResizing preferences not restoring saved widths

[johanrd]

Summary

Fix column widths not being restored from preferences adapter

Problem

saveColWidths (line 362) used a hardcoded 'ColumnResizing' string:

  const existing = tablePrefs.storage.forPlugin('ColumnResizing');

But the restore path in preferences.forColumn (base.ts:182) uses:

  const existing = prefs.storage.forPlugin(klass.name);

When bundlers mangle class names, ColumnResizing.name becomes something like '_ColumnResizing', causing a mismatch:

• Save: writes to plugins.ColumnResizing.columns...
• Restore: reads from plugins._ColumnResizing.columns...

Fix

Use ColumnResizing.name consistently for both save and restore.