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/notebook.js

@@ -84,7 +84,7 @@ function controlsHtml() {
   3. Build (3) a chamber of stone wall blocks with a one-block vent in the roof, a floor of clay Grates, and an Ingot mold right under the grates. The notebook's Blueprints tab has this as a starter design.<br>
   4. Ctrl+click coal and copper ore in the bag to blow a mix. Fly inside (the bot passes through what you build) and right click to blow an even mix onto the grates: about 50 of each. (Ore first and coal on top works too; coal buried under ore will not light.) Light a coal grain on top with the Igniter.<br>
   5. When the ingot sets, bars drop out of the bottom of the mold onto whatever is under it. Leave one open block under it: a belt below that carries them off, or pick them up with the nozzle. Leftover metal stays for the next firing. Ingot molds empty themselves: bars, junk and scrap drop below, slag is thrown away and the grate above is raked. Removing any mold returns its set metal to your bag: whole bars as bars, the rest as scrap.<br>
-  Screw tubes carry grains and whole bars: feed bars in from a belt, turn corners and unload at the mouth.<br>
+  Screw tubes carry grains and whole bars: feed bars in from a belt, turn corners and unload at the mouth. Drag at about 45° for a diagonal run; R cycles eight directions.<br>
   6. Blow the bars into the trade dock: they sell the moment they drop through its grate, and bars pay far more than ore. Watch the Market page for orders that pay double. Money buys belts, screw tubes and fans; pay down the claim there too.<br>
   7. From there: deeper ores (tin, zinc, silver, gold), alloys, fans for hotter fires, iron and steel.</p>
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