Feature/colorblind mode (#4150)

**Add approved & assigned issue number here:**

Resolves #2549

## Description:

Adds colorblind mode. Similar to dark mode, it exists as a toggle in
settings. When enabled, it swaps the game's theme (which is refactored
to extend from a theme base class) to use more colorblind-friendly
colors and brightness variations. Borders are darkened, and terrarin is
separated by lightness. Friendly/Foe colors and switched to blue/orange
instead of red/green.

The theme refactor supports adding new themes without having to
reimplement the color distribution system. New themes can extend the
BaseTheme and supply the data, such as palettes, team-color variations,
and terrain.

New setting:
<img width="880" height="273" alt="Screenshot 2026-06-04 at 11 30 27 AM"
src="https://github.com/user-attachments/assets/d5d573d5-cc64-4ac1-95c2-00627faf17cc"
/>

New color palette:
<img width="1119" height="757" alt="Screenshot 2026-06-04 at 11 30
59 AM"
src="https://github.com/user-attachments/assets/2bb15bc9-992b-41ae-ab0e-b01fe0c3c6bb"
/>

## Please complete the following:

- [X] I have added screenshots for all UI updates
- [X] I process any text displayed to the user through translateText()
and I've added it to the en.json file
- [X] I have added relevant tests to the test directory

## Please put your Discord username so you can be contacted if a bug or
regression is found:

jetaviz

src/client/render/gl/GraphicsOverrides.ts

@@ -35,6 +35,11 @@ export const GraphicsOverridesSchema = z
         fx: z.boolean(),
       })
       .partial(),
+    accessibility: z
+      .object({
+        colorblind: z.boolean(),
+      })
+      .partial(),
   })
   .partial();
 

src/client/render/gl/RenderOverrides.ts

@@ -3,6 +3,11 @@ import type { RenderSettings } from "./RenderSettings";
 
 const DARK_AMBIENT = 0.35;
 
+/**
+ * Apply the user's graphics overrides onto a RenderSettings in place: name
+ * scaling, classic/dark structure and name styling, and the colorblind-safe
+ * affiliation/tint palette.
+ */
 export function applyGraphicsOverrides(
   settings: RenderSettings,
   overrides: GraphicsOverrides,
@@ -67,8 +72,36 @@ export function applyGraphicsOverrides(
     settings.name.outlineG = channel;
     settings.name.outlineB = channel;
   }
+  if (overrides.accessibility?.colorblind === true) {
+    // Swap the red/green friend-foe encoding (the most common confusion axis)
+    // for a colorblind-safe blue/orange pairing (Okabe-Ito).
+    // Alt-view affiliation borders: self/ally in the blue family, enemy orange.
+    settings.affiliation.selfR = 0;
+    settings.affiliation.selfG = 0.447;
+    settings.affiliation.selfB = 0.698;
+    settings.affiliation.allyR = 0.337;
+    settings.affiliation.allyG = 0.706;
+    settings.affiliation.allyB = 0.914;
+    settings.affiliation.enemyR = 0.835;
+    settings.affiliation.enemyG = 0.369;
+    settings.affiliation.enemyB = 0;
+    // Normal-view relationship border tints: friendly blue, enemy orange,
+    // applied strongly so the cue doesn't rely on subtle hue.
+    settings.mapOverlay.friendlyTintR = 0;
+    settings.mapOverlay.friendlyTintG = 0.447;
+    settings.mapOverlay.friendlyTintB = 0.698;
+    settings.mapOverlay.embargoTintR = 0.835;
+    settings.mapOverlay.embargoTintG = 0.369;
+    settings.mapOverlay.embargoTintB = 0;
+    // Strong ratio so the friend/foe tint dominates the darkened territory
+    // border — neutral keeps its (darkened) fill hue, ally reads blue, enemy
+    // reads orange.
+    settings.mapOverlay.friendlyTintRatio = 0.85;
+    settings.mapOverlay.embargoTintRatio = 0.85;
+  }
 }
 
+/** Apply dark-mode lighting (ambient + enabled) onto settings when active. */
 export function applyDarkModeOverride(
   settings: RenderSettings,
   isDark: boolean,