Deepgrain Foundry: move from a claude.ai artifact to a local repository

The game as of artifact version 24, ready for local development with
coding agents.

- Source split from three large files into 52 small ones under src/sim,
  src/render and src/ui, joined in the order in src/manifest.json by
  build.py. The joined code is unchanged apart from comments; every
  headless suite gives the same output, and screenshots in both looks
  are pixel-identical to before.
- Light tidying with no change in behaviour: one movement scan loop,
  shared hazard-stripe and belt shader helpers, unused code removed, a
  shared check helper for the test suites.
- World files can be exported as an ordinary download outside claude.ai.
- Tests: broken old scripts removed, experiments moved to tools/,
  test/run_all.py added. Tools: shot.py (repeatable screenshots),
  where.py, map.py.
- Docs: AGENTS.md, CLAUDE.md, NOTES.md (the owner's to-do inbox),
  docs/PROJECT_MAP.md, DESIGN.md, TESTING.md, systems notes, the
  owner's requests and an agent log.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01K9kLmYADKSEjuwUN3rFxDA

tools/experiments/flow.js

@@ -0,0 +1,33 @@
+// Throughput of belts and screw tubes: grains delivered per second. Whatever lands
+// past the outlet is taken away, so the output pile never backs up into the line.
+const { load, flatWorld, rect, ticks, count } = require('../../test/harness');
+const { run } = load();
+const res = {};
+function fresh() { flatWorld(run, 320, 200, 120); run('bot.x = 20; bot.y = 40; money = 1e6; globalThis.__got = 0;'); }
+function rate(x0, x1, y0, y1) {
+  const sink = `for (let y=${y0};y<=${y1};y++) for (let x=${x0};x<=${x1};x++) { const i=y*W+x; if (mat[i]===SAND) { mat[i]=EMPTY; __got++; } }`;
+  for (let k = 0; k < 90; k++) run(`simTick(); ${sink}`);
+  run('__got = 0');
+  for (let k = 0; k < 300; k++) run(`simTick(); ${sink}`);
+  return run('__got') / 5;
+}
+// sideways tube fed by a walled hopper sitting on its first two blocks
+fresh();
+run('for (let bx = 20; bx < 30; bx++) placeBlock(BP_TUBE, 1, bx, 20, true);');
+run('for (let y = 0; y < 80; y++) { setCell(y*W+79, STONE, AMB[y], 0); setCell(y*W+96, STONE, AMB[y], 0); }');
+rect(run, 80, 0, 95, 79, run('SAND'));
+res.tubeSideways = rate(120, 319, 84, 119);
+res.tubeLanes = run('(() => { const s = new Set(); for (let y = 80; y < 84; y++) for (let x = 100; x < 120; x++) if (mat[y*W+x] === SAND) s.add(y); return s.size; })()');
+// lift: a column of up-tubes in a pit of sand, turned sideways at the top
+fresh();
+run('for (let y = 120; y < 196; y++) for (let x = 90; x < 130; x++) setCell(y*W+x, EMPTY, AMB[y], 0)');
+rect(run, 90, 130, 129, 195, run('SAND'));
+run('for (let by = 20; by <= 37; by++) placeBlock(BP_TUBE, 0, 26, by, true); for (let bx = 26; bx <= 40; bx++) placeBlock(BP_TUBE, 1, bx, 19, true);');
+res.lift = rate(164, 319, 80, 119);
+res.liftLanes = run('(() => { const s = new Set(); for (let y = 76; y < 80; y++) for (let x = 120; x < 160; x++) if (mat[y*W+x] === SAND) s.add(y); return s.size; })()');
+// belt: 12 blocks, a pile dropped on its back end
+fresh();
+run('for (let bx = 20; bx < 32; bx++) placeBlock(BP_BELT, 1, bx, 25, true);');
+rect(run, 80, 20, 95, 99, run('SAND'));
+res.belt = rate(128, 319, 104, 119);
+console.log(JSON.stringify(res));