Multi-block: - TerminalBlockEntity stores controllerPos for extension blocks - ScreenGroup wired into block entity and renderer - Extensions render sub-region UVs of controller's texture - Group rescans on block place/break, notifies neighbors - Controller resizes terminal for full group dimensions UX improvements: - Right-click only activates on the SCREEN face (facing direction) - Other 5 faces allow normal block placement (critical for multi-block) - Matrix-style falling green code rain animation on idle/off blocks - Animated at ~10fps with random column advancement Tests: - 2 new GameTests: multiBlockGroupFormation, differentFacingNoGroup - Visual test still passes Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>