Diagonal screw tubes, laid by a 45° drag (t35)

- Tubes run in eight directions: a drag at about 45° lays a diagonal run, R cycles all eight.
- Diagonal runs carry grains at the straight rate (120 grains/s), join straight tubes and belts,
  keep grains in at the corners, pass water, and carry bars level.
- New part ids 11-14 (saved ids are never renumbered); tube checks use an IS_TUBE table.
- New test/t_diag_tubes.js (85 checks).

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

src/ui/build-menu.js

@@ -47,7 +47,7 @@ function buildVariantChips(P) {
   const dir = P.dirs ? P.dirs[GAME.pieceDir[P.id] || 0] : null;
   // while dragging a line of belts, filters or tubes, the direction is the drag's
   const dragging = GAME.drag && GAME.dragDir >= 0 && P.dirs;
-  const glyph = d => ({ left: '←', right: '→', up: '↑', down: '↓' })[d] || '';
+  const glyph = d => ({ left: '←', right: '→', up: '↑', down: '↓', 'up-right': '↗', 'down-right': '↘', 'down-left': '↙', 'up-left': '↖' })[d] || '';
   const dirChip = !P.dirs ? '' : dragging ? `<span class="chip ok">${glyph(P.dirs[GAME.dragDir])} ${esc(P.dirs[GAME.dragDir])} · from your drag</span>` : `<span class="chip hot">${glyph(dir)} ${esc(dir)} · R</span>`;
   const fc = GAME.filterCfg;
   const sws = ms => ms.slice(0, 6).map(m => `<span class="sw" style="display:inline-block;vertical-align:-2px;width:9px;height:9px;margin-right:2px;background:${rgbOf(m)}"></span>`).join('') + (ms.length > 6 ? `+${ms.length - 6}` : '');