Tweaks blindness to be more player friendly (#94323)

## About The Pull Request

So something i missed from when i played Goonstation a long while ago
was my blind characters, i tried recreating them in TGCode but found
that the blind quirk here is far more harsh to play visually. So i got
some help from Melbert and got a plan goin and here's the results.


![blinds](https://github.com/user-attachments/assets/d12bd5c1-e0cb-4997-835f-279076c6a665)

Players can see colors! But muted, this change is strictly for visual
enjoyment as the constant monochrome is just - i cant really describe
how much i hate seeing it for more than 15 minutes.

Secondly the flicker is gone from the quirk but remains for all the
temporary blindness, this is 100% Melberts code as they're a helluva lot
smarter than I am and I just nod and smile before pasting it. This did
entail creating a new fulscreen in the dmi, but i just copy/pasted the
existing one and took out the animated frames and named it as 'static'
so it wouldnt interfere with anything else using it.

## Why It's Good For The Game

Playing a blind character is great, however it causes some serious
eyestrain after prolonged playstyle

## Changelog
🆑 MrMelbert, Zergspower
qol: The world is now heavily desaturated while blind, rather than pure
monochrome, to give players some visual stimulus
qol: When blind, the brief flicker of the entire screen now only appears
for mobs temporarily blinded - ie, mobs blinded from quirk / trauma /
genetic mutation no longer experience it
/🆑

code/modules/client/client_colour.dm

@@ -170,6 +170,14 @@
 
 // Color types
 
+///we want it to be less harsh for players to take blindness quirk, this adds enough color to not cause too much eye strain
+/datum/client_colour/blindness
+	priority = CLIENT_COLOR_HELMET_PRIORITY
+	split_filters = TRUE
+	color = list(/*R*/ 0.51,0.3,0.3,0, /*G*/ 0.29,0.51,0.29,0, /*B*/ 0.3,0.3,0.61,0, /*A*/ 0,0,0,1, /*C*/ 0,0,0,0) // dim and less saturated
+	fade_in = 2 SECONDS
+	fade_out = 2 SECONDS
+
 ///A client color that makes the screen look a bit more grungy, halloweenesque even.
 /datum/client_colour/halloween_helmet
 	priority = CLIENT_COLOR_HELMET_PRIORITY