Fixes medical grippers not being usable in surgery (#26311)

* Fixes medical grippers not being usable in surgery

* Adds a new trait for tools that behave like an open hand  in surgery. uses that instead of a typecheck.

code/modules/surgery/abstract_steps.dm

@@ -97,7 +97,7 @@
 	for(var/datum/surgery/S in branches_init)
 		first_step = S.get_surgery_step()
 
-		if(!tool && first_step.accept_hand)
+		if((!tool || HAS_TRAIT(tool, TRAIT_SURGICAL_OPEN_HAND)) && first_step.accept_hand)
 			if(SURGERY_TOOL_HAND in starting_tools)
 				CRASH("[src] was provided with multiple branches that allow an empty hand.")
 			next_surgery = S  // if there's no tool, just proceed forward.
@@ -141,7 +141,7 @@
 		if((SURGERY_TOOL_ANY in starting_tools) && next_surgery_step.accept_any_item)
 			CRASH("[src] has a conflict with the next main step [next_surgery_step] in surgery [surgery]: both accept any item.")
 
-		if(!tool && next_surgery_step.accept_hand && !(SURGERY_TOOL_HAND in starting_tools))
+		if((!tool || HAS_TRAIT(tool, TRAIT_SURGICAL_OPEN_HAND)) && next_surgery_step.accept_hand && !(SURGERY_TOOL_HAND in starting_tools))
 			next_surgery = surgery
 
 		for(var/allowed in next_surgery_step.allowed_tools)

code/modules/surgery/surgery.dm

@@ -217,9 +217,7 @@
 
 	var/success = FALSE
 	if(accept_hand)
-		if(!tool)
-			success = TRUE
-		if(isrobot(user) && istype(tool, /obj/item/gripper/medical))
+		if(!tool || HAS_TRAIT(tool, TRAIT_SURGICAL_OPEN_HAND))
 			success = TRUE
 
 	if(accept_any_item)