Fade player names under the cursor, with a graphics setting to tune it (#4221)

## Description:

Player name plates can block the view of what's underneath them
(structures, units, terrain). This PR fades the entire name plate —
name, troop count, flag, and emoji/status row — to 25% opacity while the
cursor is over it, so you can see and click what's behind it.

**How it works:**

- `HoverHighlightController` pushes the cursor's world position into the
renderer on mouse move.
- `NamePass` hit-tests the cursor against each player's name plate
bounds on the CPU (mirroring the lerp/sizing math in `name.vert.glsl`)
and passes the matched player's ID to the text, icon, and status-icon
programs, which apply the alpha multiplier in their shaders.

**Graphics setting:**

- New "Name opacity under cursor" slider in the Graphics Settings modal
(Name Labels section), range 0–1, default 0.25. Setting it to 1 disables
the fade entirely.
- Wired through the existing `GraphicsOverrides` pipeline: changes apply
live and are cleared by "Reset to defaults".
- Tuning knob exposed as `name.hoverFadeAlpha` in `render-settings.json`
and the debug GUI.

## Please complete the following:

- [ ] 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
- [ ] 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:

evan

src/client/render/gl/GameView.ts

@@ -400,6 +400,9 @@ export class GameView {
   setHighlightOwner(ownerID: number): void {
     this.renderer?.setHighlightOwner(ownerID);
   }
+  setMouseWorldPos(x: number, y: number): void {
+    this.renderer?.setMouseWorldPos(x, y);
+  }
   setHighlightStructureTypes(unitTypes: string[] | null): void {
     this.renderer?.setHighlightStructureTypes(unitTypes);
   }