makes xenos take damage when patting fire on ground (#6484)

# About the pull request

patting fire on ground now slightly harms the xeno

# Explain why it's good for the game

fire patting nerfed the area denial aspect of fire greatly, watching
xenomorph just extinqish fuel covered ground with few pats and walk
thrue it also looks stupid. this adds MINOR damage to patting fire,
making use of flames and tacticly patting them more rewarding. being
harmed to save fellow sister feels better then just clicking a tile
bunch with no risk at all.


# Testing Photographs and Procedure
<details>
<summary>Screenshots & Videos</summary>

Put screenshots and videos here with an empty line between the
screenshots and the `<details>` tags.

</details>


# Changelog
:cl:
balance: patting fire on ground harms the xeno, more intense fire means
more harm
/:cl:

---------

Co-authored-by: vincibrv <[email protected]>
Co-authored-by: kiVts <[email protected]>
Co-authored-by: Drathek <[email protected]>

code/_onclick/xeno.dm

@@ -61,6 +61,9 @@
 					var/turf/target_turf = target
 					for(var/obj/flamer_fire/fire in target_turf)
 						firepatted = TRUE
+						if(!(caste.fire_immunity & FIRE_IMMUNITY_NO_DAMAGE) || fire.tied_reagent?.fire_penetrating)
+							var/firedamage = max(fire.burnlevel - check_fire_intensity_resistance(), 0) * 0.5
+							apply_damage(firedamage, BURN, fire)
 						if((fire.firelevel > fire_level_to_extinguish) && (!fire.fire_variant)) //If fire_variant = 0, default fire extinguish behavior.
 							fire.firelevel -= fire_level_to_extinguish
 							fire.update_flame()