The editor now supports:
- Editing both buy and sell prices from a config-driven GUI.
- Adding new type: item entries to ShopGUIPlus from the item in a player's main hand.
- Removing existing shop items from the GUI or by command.
- Reloading ShopGUIPlus shop data immediately after save/remove operations.
- Configuring editor layout, action buttons, price step buttons, price limits, and add-item defaults.

Edit an existing item:
- Open a ShopGUIPlus shop.
- Shift + Right Click an item.
- Adjust prices.
- Click Save item.
- Click Remove item to delete the entry from the shop file.

Add a new item:
1. Hold the item you want to add in your main hand.
2. Run:
- /shopguipluseditor add <shop> <slot> [page] [item-id]
3. Adjust prices in the editor.
4. Click Save item.

If item-id is omitted, the plugin generates the next numeric ID from the shop file.

Remove an item directly:
- /shopguipluseditor remove <shop> <item-id>

Open the editor directly:
- /shopguipluseditor edit <shop>/<item-id>
- /shopguipluseditor edit <material> [shop]

Config Changes

config.yml now includes:

- edit-menu.size
- edit-menu.preview-slot
- edit-menu.save-button
- edit-menu.remove-button
- edit-menu.back-button
- edit-menu.buy-price-adjust-buttons.*.slot
- edit-menu.sell-price-adjust-buttons.*.slot
- new-item.default-buy-price
- new-item.default-sell-price
- new-item.default-page
- new-item.default-quantity
- new-item.copy-held-amount
- validation.buy-price.min
- validation.buy-price.max
- validation.sell-price.min
- validation.sell-price.max
- Expanded `messages.*`

Metadata Preserved When Adding Items:
The add-item serializer writes common ShopGUIPlus item fields for held items:

- material
- quantity
- name
- lore
- flags
- damage
- enchantments
- unbreakable
- customModelData
- potion
- patterns
- skin

Current Limits:
- The add flow creates standard ShopGUIPlus type: item entries.
- It does not generate type: command, type: permission, or other custom action entries from held items.
- Custom provider IDs such as nexo, oraxen, itemsadder, and similar plugin-specific item references are not reconstructed from held items. Those still need manual config work if you want provider-native entries.