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

src/sim/tick.js

@@ -0,0 +1,25 @@
+// simTick: one simulation step, in order.
+// ---------- Main tick ----------
+function simTick() {
+  tick++;
+  tickStamp = (tickStamp % 255) + 1;
+  if (tick % 20 === 1) updateRoof();
+  weatherTick();
+  machinesTick();
+  pipesTick();
+  pulseTick();
+  entTick();
+  if (flyers.length) flyTick();
+  simMove();
+  heatPass();
+  for (let c = 0; c < NCH; c++) if (awake[c]) awake[c]--;
+  if (tick % 15 === 0) checkMolds();
+  if (tick % 30 === 0) checkLedger();
+  if (tick % 60 === 7) plantTick();
+  if (tick % 120 === 13) coldTick();
+  if (tick % 20 === 9 && treeBases.length) treeSupportTick();
+  dockTick();
+  if (tick % 60 === 17) { marketTick(); ordersTick(); }
+  if (tick % 30 === 11 && saplings.length) saplingTick();
+  ghostTick();
+}