Kneejerk: The Kneejerkening (#91342)

## About The Pull Request
OH BOY HERE I GO REDUCING MY GBP AGAIN
Adds a reflex hammer, used to test your kneejerk reflex. Makes it
printable from auto, med, and sci lathes, as with other basic medical
tools. It looks like this:

![reflexhammer](https://github.com/user-attachments/assets/5a965e17-9995-4092-ba29-a20e52880170)




(i stopped doing web edits are you happy)
## Why It's Good For The Game
This is a simple and useful way to measure brain health. Usually you'd
need either a rare toy, a null rod, or the one per map gavel. This makes
analog diagnosis easier and more fun!
## Changelog
🆑
add: Reflex Hammer, used to test your kneejerk reflex. Print one now,
from your local lathe!
/🆑

---------

Co-authored-by: ThrowawayUseless <notarealemail@emailservice.fake>

code/modules/research/techweb/nodes/medbay_nodes.dm

@@ -30,6 +30,7 @@
 		"pillbottle",
 		"xlarge_beaker",
 		"jerrycan",
+		"reflex_hammer",
 	)
 	experiments_to_unlock = list(
 		/datum/experiment/autopsy/human,