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/data/gameplay/repairGameConfig.ts

@@ -3,3 +3,22 @@ export const REPAIR_FRAGMENTATION_SEQUENCE_SECONDS = 4;
 export const REPAIR_INTERACTION_RADIUS = 10;
 export const REPAIR_SCAN_PART_SECONDS = 1.2;
 export const REPAIR_REASSEMBLY_SECONDS = 1.4;
+/**
+ * Lerp speed used by the shared ExplodableModel during the repair flow.
+ * Lower = slower, more deliberate explosion so the player can see each
+ * node clearly leave its original position. The default ExplodedModel
+ * speed (6) finishes in ~0.5s which feels rushed.
+ */
+export const REPAIR_FRAGMENT_SPLIT_SPEED = 1.8;
+/**
+ * Delay between the end of the inverse-explosion (parts settled back to
+ * their original positions) and the auto-transition to the `done` step.
+ * Used by the ebike repair flow so the reassembly particles can play
+ * before the bubble starts shrinking.
+ */
+export const REPAIR_REASSEMBLY_HOLD_MS = 1500;
+/**
+ * Fallback timer for the ebike `done` -> mission-complete transition
+ * when the narrator audio fails to fire its `ended` event.
+ */
+export const REPAIR_DONE_DIALOGUE_FALLBACK_MS = 6000;