Fish electrogenesis now scales with size. (#86593)

## About The Pull Request
A little touch to fish electrogenesis. Now its power scales with the
size of the fish. The initial values for the zip zap and the jumpercable
have been edited so that their average output is more or less
unaffected.

This PR also adds a check to fish petting to ensure that the user is
shocked only if the fish actually has the electrogenesis trait and not
just the energy that'd be generated if the fish had the trait.

## Why It's Good For The Game
The size and weight of a fish are variables that influence a lot of
mechanics such as reagents, number of fillets, weight class, force,
slowdown when carried or dragged, other traits, cargo value.
Electrogenesis should be no different.

Also fixing a possible oversight (not in the changelog because so far
the only fish with over 15 MJ is the zip zap and it's about impossible
to remove their electrogenesis trait rn also because they don't
reproduce).

## Changelog

🆑
balance: Fish electrogenesis now scales with size.
/🆑

code/modules/fishing/fish/_fish.dm

@@ -142,8 +142,8 @@
 	var/experisci_scannable = TRUE
 	/// cooldown on creating tesla zaps
 	COOLDOWN_DECLARE(electrogenesis_cooldown)
-	/// power of the tesla zap created by the fish in a bioelectric generator
-	var/electrogenesis_power = 10 MEGA JOULES
+	/// power of the tesla zap created by the fish in a bioelectric generator. Scales with size.
+	var/electrogenesis_power = 2 MEGA JOULES
 
 	/// The beauty this fish provides to the aquarium it's inserted in.
 	var/beauty = FISH_BEAUTY_GENERIC
@@ -234,6 +234,7 @@
 		if(size > FISH_SIZE_TWO_HANDS_REQUIRED)
 			qdel(GetComponent(/datum/component/two_handed))
 	size = new_size
+	electrogenesis_power = initial(electrogenesis_power) * size * 0.1
 	var/init_icon_state = initial(inhand_icon_state)
 	switch(size)
 		if(0 to FISH_SIZE_TINY_MAX)
@@ -863,7 +864,7 @@
 	if(recently_petted)
 		to_chat(user, span_warning("[src] runs away from your finger as you dip it into the water!"))
 		return
-	if(electrogenesis_power > 15 MEGA JOULES)
+	if(HAS_TRAIT(src, TRAIT_FISH_ELECTROGENESIS) && electrogenesis_power > 15 MEGA JOULES)
 		user.electrocute_act(5, src) //was it all worth it?
 	recently_petted = TRUE
 	SEND_SIGNAL(src, COMSIG_FISH_PETTED)

code/modules/fishing/fish/types/freshwater.dm

@@ -139,7 +139,7 @@
 		/datum/fish_trait/electrogenesis,
 	)
 	//anxiety naturally limits the amount of zipzaps per tank, so they are stronger alone
-	electrogenesis_power = 20 MEGA JOULES
+	electrogenesis_power = 6.7 MEGA JOULES
 	beauty = FISH_BEAUTY_GOOD
 
 /obj/item/fish/tadpole

code/modules/fishing/fish/types/syndicate.dm

@@ -46,6 +46,7 @@
 		/datum/fish_trait/mixotroph,
 		/datum/fish_trait/electrogenesis,
 	)
+	electrogenesis_power = 0.9 MEGA JOULES
 	beauty = FISH_BEAUTY_UGLY
 
 /obj/item/fish/chainsawfish