feat(repair): introduce focus bubble shroud for repair mini-game

Adds a dark expanding sphere around the repair model when the player
enters the immersive repair phases (fragmented / scanning / repairing /
reassembling). The bubble grows from 0 to 10m using GSAP expo.out over
2.5s and reverses on focus end, visually isolating the player from the
surrounding map.

- New useRepairFocusStore tracks active state + world center.
- New RepairFocusBubble renders a BackSide sphere shell + a soft cocoon
  decor pass (grid floor + directional light + ambient) inside.
- RepairGame drives setFocus from its lifecycle effect.
- Mounted in both GameStageContent and TestMap so behaviour matches in
  the production scene and the physics test scene.

Also drops the now-unused EBIKE_CONFIG_KEY constant in
GameStageContent.tsx (leftover from a previous remount-key strategy).

src/components/three/gameplay/RepairGame.tsx

@@ -25,6 +25,7 @@ import type {
   RepairScannedBrokenPart,
 } from "@/types/gameplay/repairMission";
 import { useGameStore } from "@/managers/stores/useGameStore";
+import { useRepairFocusStore } from "@/managers/stores/useRepairFocusStore";
 import type { ModelTransformProps, Vector3Tuple } from "@/types/three/three";
 import { toVector3Scale } from "@/utils/three/scale";
 
@@ -110,6 +111,25 @@ export function RepairGame({
     };
   }, [mainState, mission, step]);
 
+  // Drive the global focus bubble: active during the immersive repair
+  // phases so the world dims/hides outside the dark sphere shroud.
+  const focusCenterX = snappedPosition[0];
+  const focusCenterY = snappedPosition[1];
+  const focusCenterZ = snappedPosition[2];
+  useEffect(() => {
+    const inFocusPhase =
+      mainState === mission && shouldFocusBubbleBeActive(step);
+    if (inFocusPhase) {
+      useRepairFocusStore
+        .getState()
+        .setFocus(true, [focusCenterX, focusCenterY, focusCenterZ]);
+      return () => {
+        useRepairFocusStore.getState().setFocus(false);
+      };
+    }
+    return undefined;
+  }, [mainState, mission, step, focusCenterX, focusCenterY, focusCenterZ]);
+
   useEffect(() => {
     if (mainState !== mission) return undefined;
 
@@ -214,6 +234,15 @@ function shouldKeepRepairRuntimeState(step: MissionStep): boolean {
   return step === "repairing" || step === "reassembling" || step === "done";
 }
 
+function shouldFocusBubbleBeActive(step: MissionStep): boolean {
+  return (
+    step === "fragmented" ||
+    step === "scanning" ||
+    step === "repairing" ||
+    step === "reassembling"
+  );
+}
+
 function getRepairMissionModelPaths(config: RepairMissionConfig): string[] {
   return [
     ...new Set([