refactor(ebike): drop redundant 'locked' substate, single entry trigger

The ebike mission previously had two redundant entry-point sub-states
('locked' and 'waiting') that were behaviorally identical from the
player's perspective:
- both showed the same 'Lancer le Repair Game' prompt
- both allowed the press-E handler in Ebike.tsx to jump to 'inspected'

In addition, the locked state caused two latent bugs:
- the static-map ebike node (GameMap) and the live <Ebike> component
  were rendered simultaneously at the same world position
- a generic RepairMissionTrigger anchor sphere was rendered in
  parallel to Ebike's own InteractableObject (two triggers, same area)

Changes:
- useGameStore: ebike's initial currentStep + completeIntroState target
  is now 'waiting' (pylon/farm still init at 'locked' — they need it).
- Ebike.tsx: drop dead === 'locked' branches in repairGameOwnsEbikeModel
  and the press-E handler.
- EbikeRepairNarrator: only reset the played-set on 'waiting'.
- RepairGame: drop 'locked' from the ebike livePosition guard.
- REPAIR_MISSION_TRIGGERS: empty array (the duplicate ebike anchor
  sphere is gone). Keep the array + RepairMissionTrigger component for
  future re-use.
- GameMap: hide the static-map ebike node as soon as
  mainState === 'ebike' (was: only when ebikeStep !== 'locked').
- repairMissionState.getPreviousMissionStep: ebike rewinds from
  'waiting' to 'waiting' (cap), pylon to 'npc-return', farm to 'locked'.

The 'locked' value is intentionally kept in the MissionStep type union
because the farm mission still uses it as a meaningful kickoff state
driving FarmNarrativeFlow's auto-transition to electricienne_history.

src/world/GameMap.tsx

@@ -323,9 +323,11 @@ function MapNodeInstance({
 }): React.JSX.Element | null {
   const isGeneratedModel = isGeneratedMapModelName(node.name);
   const mainState = useGameStore((state) => state.mainState);
-  const ebikeStep = useGameStore((state) => state.ebike.currentStep);
-  const hideEbikeMapModel =
-    node.name === "ebike" && mainState === "ebike" && ebikeStep !== "locked";
+  // The static-map ebike node is replaced by the live `Ebike` component
+  // (rendered from GameStageContent) as soon as the ebike mission begins,
+  // so hide the static one to avoid a dual-render at the same world
+  // position.
+  const hideEbikeMapModel = node.name === "ebike" && mainState === "ebike";
 
   useEffect(() => {
     if (modelUrl !== null || isGeneratedModel) return;