Render the exploded mission model during the repairing step so broken
nodes (e.g. ebike refroidisseur) stay visible in the world, and surface
their world positions to RepairRepairingStep so broken pieces spawn
from where they belong on the model rather than from a static offset.
- ExplodableModel: add hideNodeNames (mesh visibility off, restored on
unmount) and nodeAnchorNames + onNodeAnchorsChange (per-frame world
positions debounced via signature so React state updates only when
the values actually move).
- RepairGame: render ExplodableModel during 'repairing' with the broken
node names hidden + anchors forwarded; threads brokenAnchors state
to RepairRepairingStep.
- RepairScanSequence + RepairRepairingStep: propagate targetNodeName
through scanned and fallback broken-part lists.
- RepairRepairingStep: broken parts spawn at brokenAnchors[targetNodeName]
when set, falling back to legacy BROKEN_PART_START_OFFSETS otherwise.
Tom Boullay