Belts are no longer placed on hover during a drag. Left-press anchors the
drag; as the cursor moves, a rectilinear (L-shaped) path of belt ghosts is
previewed from the anchor to the cursor — first leg parallel to the belt's
current orientation, then orthogonal — with each tile auto-oriented to follow
the path. Construction sites are placed on release: new valid tiles are placed
(subject to cumulative affordability), tiles holding only a belt are re-oriented
in place, and occupied/invalid tiles are skipped. Unaffordable tiles show no
ghost. Right-click during a drag cancels it without leaving belt build mode.
Path geometry is factored into a pure computeBeltDragPath() in lib/core with
Catch2 coverage; GameWorldView owns the classification, affordability, and
rendering against live sim state.
Implements REQ-BLD-BELT-DRAG.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Y7N59FsLA5e2kuVdqe4Uhc
