refactor(repair): unify exploded model across phases, simplify ebike flow

- RepairGame: lift a single ExplodableModel mounted across fragmented
  -> done so the model loads once, animates from its real original
  positions, and never re-instantiates between phases. Eliminates the
  position/rotation jumps and re-explosion that occurred when each
  step instantiated its own model.
- ExplodableModel: expose splitSpeed prop so the explode/reassemble
  lerp can be slowed down (REPAIR_FRAGMENT_SPLIT_SPEED = 1.8) for a
  more deliberate visual where each node is seen leaving its origin.
- RepairScanSequence: drop its own ExplodableModel, receive parts
  from the upstream shared instance. Logs the available part names
  when broken-part nodes can't be matched so config drift is visible.
- RepairReassemblyStep: reduced to the completion particles + a
  delayed onSettled callback. The collapse animation is now driven by
  the shared ExplodableModel switching split=false at the reassembling
  phase. After REPAIR_REASSEMBLY_HOLD_MS (1500ms) the upstream flow
  auto-advances to done.
- RepairEbikeRepairTrigger: new minimal interactable for the ebike
  repairing step. Replaces the heavier grabbable-parts UX (cercles,
  ranger pieces) with a single 'Changez le refroidisseur' prompt that
  advances directly to reassembling. Pylon/farm keep RepairRepairingStep.
- RepairCompletionStep: drop the duplicated RepairObjectModel; the
  shared ExplodableModel renders the repaired model at done.
- RepairGame ebike-done: play narrateur_ebikerepare and call
  completeMission on the audio's ended event (with REPAIR_DONE_DIALOGUE_FALLBACK_MS
  fallback). Hands off to pylon without a Validate button.
- EbikeRepairNarrator: drop the done entry; RepairGame owns it now so
  the audio's end event can drive the mission completion handoff.
- RepairGame: drop the window.ebikeParkedPosition livePosition logic.
  Ebike movement is disabled during the repair flow so the static zone
  position is the source of truth, fixing the floating-bike issue
  observed in TestMap.

src/components/three/gameplay/RepairEbikeRepairTrigger.tsx

@@ -0,0 +1,34 @@
+import { TriggerObject } from "@/components/three/interaction/TriggerObject";
+import { REPAIR_INTERACTION_RADIUS } from "@/data/gameplay/repairGameConfig";
+import type { Vector3Tuple } from "@/types/three/three";
+
+interface RepairEbikeRepairTriggerProps {
+  onRepair: () => void;
+}
+
+const TRIGGER_POSITION: Vector3Tuple = [0, 1.4, 0];
+
+/**
+ * Minimal interactable used for the ebike `repairing` step. Replaces
+ * the heavier RepairRepairingStep (grabbable parts + placeholder
+ * circles) with a single "Changez le refroidisseur" prompt. The
+ * collider is invisible — the player just walks up and presses E.
+ */
+export function RepairEbikeRepairTrigger({
+  onRepair,
+}: RepairEbikeRepairTriggerProps): React.JSX.Element {
+  return (
+    <TriggerObject
+      position={TRIGGER_POSITION}
+      colliders="ball"
+      label="Changez le refroidisseur"
+      radius={REPAIR_INTERACTION_RADIUS}
+      onTrigger={onRepair}
+    >
+      <mesh>
+        <sphereGeometry args={[0.6, 16, 16]} />
+        <meshBasicMaterial colorWrite={false} depthWrite={false} />
+      </mesh>
+    </TriggerObject>
+  );
+}