fix: insert new columns before actions column in stored order

[Rishavraaj]

Summary

• New columns added to companies and deals tables were appearing after the action column instead of before it
• Root cause: useColumnOrder appends unseen columns to the end of the stored localStorage order, but actions was already at the end of that
  stored order
• Fix: split the stored order at actions, insert new columns before it, then re-append actions last

Test plan

• Add a new custom column to Contacts — verify it appears before the Actions column
• Add a new custom column to Companies — verify it appears before the Actions column
• Add a new custom column to Deals — verify it appears before the Actions column
• Reload the page after adding a column — verify order is preserved correctly
• Drag to reorder columns — verify Actions stays at the end and cannot be moved before data columns