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/components/three/gameplay/RepairGame.tsx

@@ -74,13 +74,13 @@ export function RepairGame({
     readonly RepairScannedBrokenPart[]
   >([]);
   // For the ebike mission, use the bike's live parked world position once
-  // the repair flow leaves the waiting/locked phase so the repair happens
+  // the repair flow leaves the waiting phase so the repair happens
   // wherever the player parked the bike, not at the static zone anchor.
   // window.ebikeParkedPosition is set by Ebike when the player drops the
   // bike and stays stable through the rest of the repair flow.
   const livePosition = useMemo<Vector3Tuple>(() => {
     if (mission !== "ebike" || mainState !== mission) return position;
-    if (step === "locked" || step === "waiting") return position;
+    if (step === "waiting") return position;
     const parked = window.ebikeParkedPosition;
     if (!parked) return position;
     return [parked[0], parked[1], parked[2]];