Add item use command

Docs/TechnicalDesignDocument.md

@@ -114,6 +114,15 @@ creates a separate inventory slot. It intentionally does not re-merge the split
 stack through `AddItem`, because the UI needs an actual separate stack to
 support later drag/drop and partial drop flows.
 
+MVP item use is available through `AgrarianUseItem ItemId Quantity`. The command
+routes to the server, extracts the requested stack quantity, applies a
+whitelisted item effect, and restores the stack if the item is not usable yet.
+For the first survival loop, `food` restores hunger, `meat` restores more hunger
+but adds sickness risk because it is raw, and `bandage` reduces injury severity
+with a small health bump. This gives UI item-use work a concrete authority path
+while leaving tools, structures, and future complex consumables blocked until
+they have explicit gameplay rules.
+
 ## Time And Environment
 
 The MVP gameplay calendar target is: