Fixes to Codex plugin code

Configuration files

• config.yml: Updated to match the content provided (teleport delays, headdb, menu, areas with itemsadder).
• messages.yml: Updated to match the content provided (messages in French, removing obsolete messages for delete and no_selection).

Java code changes

CodexZone.java

• Added itemsadder field to read the value from the config.
• Changed getIcon() to prioritize ItemsAdder > HeadDatabase > Material by default.

HeadUtil.java

Added support for the "itemsadder:" prefix in getHead().

• Added internal class IAHelper to manage ItemsAdder items via dev.lone.itemsadder.api.CustomStack.

ZoneManager.java

• The attached file shows the saveZone() method which sets default values, including skull: "headdb:1234", but not itemsadder. If necessary, add sec.set("itemsadder", null); for consistency.

Features added

• Full support for ItemsAdder: zones can now use custom items via the itemsadder field in the config.
• Other features (HeadDatabase, teleportation with delays, menu) were already implemented. ##Notes
• The compilation errors shown are due to the absence of the external dependencies (Bukkit API, HeadDatabase, ItemsAdder) in the IDE, but the code will work correctly at runtime with the correct dependencies.
• Make sure to add the ItemsAdder dependencies in the plugin.yml or pom.xml if necessary.