Deliberate Grid Line; Procedural Road Removed

Same audit/backfill as Iteration 48.

• Removed the legacy procedural dirt road (a full pathfinding + cart-rut rendering system) as a visual inconsistency alongside the real tile art from Iteration 48, not requested to be replaced with anything.
• Re-added a grid line as a deliberate, explicit design element (communicates the grid-based game, and doubles as visual cover for any remaining microscopic tile-art inconsistency) -- drawn correctly this time as one line per grid edge in raw device-pixel space rather than the per-cell strokeRect removed in Iteration 50, so it can't reintroduce that bug. Tuned from a dark line to a faint white glow, then brightened for visibility per direct feedback. gone and the grid line is crisp and consistent).