feat(client): highlight small players with a pulsing glow (#4525)

## Description:

Adds a **"Highlight small players"** client setting (in the in-game
Settings menu). When it's on, human players holding **0.2% or less of
the map** get a soft red glow that breathes (a pulsing aura) around
their territory, starting **one minute into the game**. This makes
near-eliminated players easy to spot on a busy map, even when their
territory is scattered in fragments or sitting under structures.

How it works:

- **Purely client-side**, no simulation or determinism impact.
`SmallPlayerGlowPass` renders a tile-space bloom: extract a sub-tile
mask of the small players' tiles, run a separable Gaussian blur, then
composite the soft aura over the map additively. It's camera-independent
(no shimmer when panning/zooming), so scattered tiles blur into one
clean halo. The aura breathes: its intensity fades fully to 0 at the
trough for clear contrast.
- The set is recomputed each tick in `WebGLFrameBuilder`: alive human
players with `tilesOwned / (landTiles - fallout) <= 0.002` (0.2%),
suppressed during the spawn phase and the first minute.
- Backed by a persisted `UserSettings` flag, toggleable live from the
in-game Settings modal (with a new, distinct icon).
- Drawn after the structure passes so buildings can't hide it.
- Mirrors the existing FalloutBloom pipeline and reuses the shared blur
shader and render-target helpers rather than duplicating them. Tunable
via `render-settings.json` (`smallPlayerGlow`: color / alpha /
pulseSpeed).

UI (glow fades in and out):
<img width="474" height="334" alt="image"
src="https://github.com/user-attachments/assets/2b94f292-2cbb-43d3-82fb-f274d1afdedf"
/>
<img width="976" height="400" alt="image"
src="https://github.com/user-attachments/assets/f1b972d7-e046-4f7a-ab43-da1eb758c7b5"
/>


## 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:

zixer._

src/core/game/UserSettings.ts

@@ -139,6 +139,10 @@ export class UserSettings {
     return this.getBool("settings.emojis", true);
   }
 
+  highlightSmallPlayers() {
+    return this.getBool("settings.highlightSmallPlayers", false);
+  }
+
   performanceOverlay() {
     return this.getBool(PERFORMANCE_OVERLAY_KEY, false);
   }
@@ -191,6 +195,13 @@ export class UserSettings {
     this.setBool("settings.emojis", !this.emojis());
   }
 
+  toggleHighlightSmallPlayers() {
+    this.setBool(
+      "settings.highlightSmallPlayers",
+      !this.highlightSmallPlayers(),
+    );
+  }
+
   // Performance overlay specifically needs a direct setter for Shift-D
   setPerformanceOverlay(value: boolean) {
     this.setBool(PERFORMANCE_OVERLAY_KEY, value);