Light Sensitivity Refactor (#22386)

The last time the Light Sensitivity code was changed, I remarked in a
review that "This should probably be a component so that its code isn't
being run on every mob forever". Well I've gotten around to doing that
myself, except I figured out it's even better off as an Element in this
situation rather than a Component. So this is now my first time adding
Elements to the repo. It turns out they're really awesome when paired
with signals.

This PR removes the hardcoded check for the light senstivity and dark
phobia traits from the Life() path, replacing them instead with two
Elements which hook into the pre-existing signal used to handle vision
updates for human mobs. I've mainly done this to help cut down on the
overwhelmingly high cost of the Life() codepath, which is currently one
of the most expensive paths we have.

While I was at it with refactoring these two, I noticed that there
wasn't a trait selection for either of them, so I added selections for
both traits to the disabilities tab so that players can opt-in to being
light sensitive or afraid of the dark!

<img width="318" height="336" alt="image"
src="https://github.com/user-attachments/assets/a1e60e83-d899-44df-8ea3-0cd5a87c231c"
/>

code/modules/mob/abstract/new_player/character_traits.dm

@@ -4,63 +4,63 @@
 	var/name = "Enigma"
 	var/desc = "This trait was not meant to be seen by mortal minds."
 
-/datum/character_disabilities/proc/apply_self(var/mob/living/carbon/human/H)
+/datum/character_disabilities/proc/apply_self(mob/living/carbon/human/H)
 	return
 
 /datum/character_disabilities/nearsighted
 	name = "Nearsightedness"
 	desc = "Without prescription glasses your vision is impaired."
 
-/datum/character_disabilities/nearsighted/apply_self(var/mob/living/carbon/human/H)
+/datum/character_disabilities/nearsighted/apply_self(mob/living/carbon/human/H)
 	H.disabilities |= NEARSIGHTED
 
 /datum/character_disabilities/stutter
 	name = "Stuttering"
 	desc = "You have a chronic case of stuttering, repeating sounds involuntarily."
 
-/datum/character_disabilities/stutter/apply_self(var/mob/living/carbon/human/H)
+/datum/character_disabilities/stutter/apply_self(mob/living/carbon/human/H)
 	H.disabilities |= STUTTERING
 
 /datum/character_disabilities/deuteranomaly
 	name = "Deuteranopia"
 	desc = "You have difficulty perceiving green."
 
-/datum/character_disabilities/deuteranomaly/apply_self(var/mob/living/carbon/human/H)
+/datum/character_disabilities/deuteranomaly/apply_self(mob/living/carbon/human/H)
 	H.add_client_color(/datum/client_color/deuteranopia, TRUE)
 
 /datum/character_disabilities/protanopia
 	name = "Protanopia"
 	desc = "You have difficulty perceiving red."
 
-/datum/character_disabilities/protanopia/apply_self(var/mob/living/carbon/human/H)
+/datum/character_disabilities/protanopia/apply_self(mob/living/carbon/human/H)
 	H.add_client_color(/datum/client_color/protanopia, TRUE)
 
 /datum/character_disabilities/tritanopia
 	name = "Tritanopia"
 	desc = "You have difficulty perceiving green and yellow."
 
-/datum/character_disabilities/tritanopia/apply_self(var/mob/living/carbon/human/H)
+/datum/character_disabilities/tritanopia/apply_self(mob/living/carbon/human/H)
 	H.add_client_color(/datum/client_color/tritanopia, TRUE)
 
 /datum/character_disabilities/total_colorblind
 	name = "Total Colorblindness"
 	desc = "You cannot see color, only black, white, and shades of gray."
 
-/datum/character_disabilities/total_colorblind/apply_self(var/mob/living/carbon/human/H)
+/datum/character_disabilities/total_colorblind/apply_self(mob/living/carbon/human/H)
 	H.add_client_color(/datum/client_color/monochrome, TRUE)
 
 /datum/character_disabilities/deaf
 	name = "Deafness"
 	desc = "You are unable to percieve sound."
 
-/datum/character_disabilities/deaf/apply_self(var/mob/living/carbon/human/H)
+/datum/character_disabilities/deaf/apply_self(mob/living/carbon/human/H)
 	H.sdisabilities |= DEAF
 
 /datum/character_disabilities/asthma
 	name = "Asthma"
 	desc = "You are prone to inflammation in the lungs."
 
-/datum/character_disabilities/asthma/apply_self(var/mob/living/carbon/human/H)
+/datum/character_disabilities/asthma/apply_self(mob/living/carbon/human/H)
 	H.disabilities |= ASTHMA
 	if(H.max_stamina)
 		H.max_stamina *= 0.8
@@ -72,7 +72,7 @@
 	/// This takes a TRAIT_DISABILITY_* type trait, and assigns it to the character on apply_self
 	var/trait_type = TRAIT_DISABILITY_HEMOPHILIA
 
-/datum/character_disabilities/hemophilia/apply_self(var/mob/living/carbon/human/H)
+/datum/character_disabilities/hemophilia/apply_self(mob/living/carbon/human/H)
 	ADD_TRAIT(H, trait_type, DISABILITY_TRAIT)
 
 /datum/character_disabilities/hemophilia/major
@@ -85,7 +85,7 @@ ABSTRACT_TYPE(/datum/character_disabilities/organ_scarring)
 	name = "Organ Scarring"
 	var/affected_organ
 
-/datum/character_disabilities/organ_scarring/apply_self(var/mob/living/carbon/human/target)
+/datum/character_disabilities/organ_scarring/apply_self(mob/living/carbon/human/target)
 	var/obj/item/organ/internal/affecting = target.internal_organs_by_name[affected_organ]
 	if(affecting)
 		affecting.set_max_damage(initial(affecting.max_damage) * 0.5)
@@ -111,7 +111,7 @@ ABSTRACT_TYPE(/datum/character_disabilities/broken)
 	name = "Bruised Limb"
 	var/affected_limb
 
-/datum/character_disabilities/broken/apply_self(var/mob/living/carbon/human/target)
+/datum/character_disabilities/broken/apply_self(mob/living/carbon/human/target)
 	var/obj/item/organ/external/affecting = target.get_organ(affected_limb)
 	if(affecting)
 		affecting.fracture(silent = TRUE)
@@ -141,7 +141,7 @@ BROKEN_DISABILITY(right_foot, "Right Foot", BP_R_FOOT)
 		+ "Though this does not grant any psychic abilities, a character with this trait is counted as being psychic for a variety of effects." \
 		+ "For example, having the ability to distinguish the source of telepathic signals, but also taking bonus damage from anything that deals bonus damage to psychics."
 
-/datum/character_disabilities/high_psi_sensitivity/apply_self(var/mob/living/carbon/human/H)
+/datum/character_disabilities/high_psi_sensitivity/apply_self(mob/living/carbon/human/H)
 	H.AddComponent(HIGH_PSI_SENSITIVITY_COMPONENT)
 
 /datum/character_disabilities/low_psi_sensitivity
@@ -151,5 +151,20 @@ BROKEN_DISABILITY(right_foot, "Right Foot", BP_R_FOOT)
 		+ "For example, losing the ability to distinguish the source of telepathic signals, or taking brain damage when having their mind read." \
 		+ "On the opposite end of the spectrum, anything that deals bonus damage to psychics will also deal reduced damage to you."
 
-/datum/character_disabilities/low_psi_sensitivity/apply_self(var/mob/living/carbon/human/H)
+/datum/character_disabilities/low_psi_sensitivity/apply_self(mob/living/carbon/human/H)
 	H.AddComponent(LOW_PSI_SENSITIVITY_COMPONENT)
+
+/datum/character_disabilities/photosensitivity
+	name = "Photosensitivity"
+	desc = "You are highly sensitive to bright lights. " \
+		+ "Characters with this trait suffer from painful sensations and degraded vision when standing in brightly lit areas without eye protection. "
+
+/datum/character_disabilities/photosensitivity/apply_self(mob/living/carbon/human/H)
+	H.AddElement(/datum/element/light_sensitivity)
+
+/datum/character_disabilities/nyctophobia
+	name = "Nyctophobia"
+	desc = "You have a fear of the dark."
+
+/datum/character_disabilities/nyctophobia/apply_self(mob/living/carbon/human/H)
+	H.AddElement(/datum/element/dark_afraid)