fix(ebike): unlock walking during breakdown + hide interact prompt + 450m ride

Three fixes for the ebike-breakdown substep:

1. PlayerController: the previous `if (!isEbikeBreakdown)` guard
   zeroed _wishDir for everyone during breakdown, including the
   player after they had been auto-dismounted to walk mode. Narrow
   the guard to `isEbikeMounted && isEbikeBreakdown` so the bike
   stops accepting drive input but the player on foot can move.

2. Ebike: track `window.ebikeBreakdownActive` in component state
   and hide the InteractableObject (and therefore the interact
   prompt UI) while the breakdown sequence is active. The bike must
   read as inert and non-interactive while the panne dialogue plays
   and during the auto-dismount that follows.

3. ebikeConfig: bump EBIKE_INTRO_BREAKDOWN_DISTANCE from 15 m to
   450 m so the panne triggers after a real ride instead of a few
   meters from the parked spawn.

src/world/player/PlayerController.tsx

@@ -363,7 +363,11 @@ export function PlayerController({
     }
 
     _wishDir.set(0, 0, 0);
-    if (!isEbikeBreakdown) {
+    // Block drive input only when still on the bike during breakdown.
+    // Once auto-dismounted (movementMode === "walk"), the player must
+    // remain free to walk around even though ebikeBreakdownActive is true.
+    const blockDriveInput = isEbikeMounted && isEbikeBreakdown;
+    if (!blockDriveInput) {
       if (keys.current.forward) _wishDir.add(_forward);
       if (keys.current.backward) _wishDir.sub(_forward);
       if (!isEbikeMounted) {