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

docs/systems/dig-tools.md

@@ -0,0 +1,86 @@
+# Dig tools: decisions
+
+Decided 2026-10-19. The resonance drill went in on 2026-10-20, and the same day its widths were
+reworked so that each one has a use. Handling of stray bits was added on 2026-10-22 and revised
+the same day: rock too hard for the bit never crumbles, and world generation makes no tiny hard
+specks instead. The code is in `src/sim/drill.js` and `src/sim/worldgen.js` (`clearHardSpecks`).
+
+## Main tool: Resonance drill
+It replaced the old "darken and delete" drill cursor.
+
+- **How it works.**
+  - Holding the button sends pulses from the bot toward the cursor.
+  - Each pulse is a fan of rays leaving the whole face of the bot, so rock right beside the bot
+    is hit too.
+  - Rock a pulse passes through shakes: it pales, shivers, and shows cracks that grow finer as
+    it nears breaking. Then it shatters into its loose grains.
+  - The pulse loses energy as it goes deeper.
+- **Pulse width** is changed on the fly with Q/E while the drill is selected. Each width has its
+  own reach.
+
+  | Width | Shape | Reach | Good for |
+  |---|---|---|---|
+  | Narrow | A beam a little wider than the bot | ×1.45 the bit's reach | The fastest and longest tunnels, big enough to fly down |
+  | Medium (default) | A cone | ×1 | General digging |
+  | Wide | A broad fan | ×0.7 | Opening the most rock per second, but only close to the bot |
+
+  Measured with a stone bit, moving with the face: narrow tunnels about 13 grains a second,
+  medium about 9, and wide about 7. Wide opens the most rock per second.
+- **Tuning** (R over a material, R again to untune): the pulse passes through everything else
+  and shatters only that material.
+- **Loose grains** a pulse passes are jostled back toward the bot, so a shattered vein pours out
+  of the wall and a bore clears itself.
+- **Hardness and base reach** still come from the cast bit tiers: stone, copper, iron, steel.
+- **Built blocks, machines and molds** soak up pulses unharmed and shield what is behind them.
+- **Trees** in the path come apart into wood chunks (not with a tuned pulse).
+- **The bot** never moves loose material. Sand, rubble and water pass straight through it.
+
+### Stray bits
+Most leftover obstacles were specks of rock too hard for the current bit, such as iron ore or
+granite inside stone when you have a stone bit.
+
+The rule: **rock too hard for your bit never breaks, crumbles or comes loose, however small.**
+Crumbling it into ore would let players get ore without the right bit, and confuse them.
+Crumbling it into stone would lose ore.
+
+These keep specks out of the way instead:
+- **World generation makes no tiny hard specks.**
+  - Iron and zinc come in fewer, chunkier veins, with the same total ore.
+  - Any piece of 30 grains or fewer that is harder than the rock around it becomes that rock
+    (`SPECK_MIN`).
+  - Older saves get this cleanup once, when loaded.
+  - Basalt dikes in the granite were removed, because they walled off parts of it.
+- **Cut-off pieces fall apart.** When a grain breaks and leaves a piece of natural rock of 16
+  grains or fewer touching nothing else, the piece falls into its loose grains. This only happens
+  if the bit could break every grain of it. A piece with too-hard rock in it stays whole.
+- **Thin rock breaks faster.** Corners, nubs and slivers with open space on two or more sides
+  shake apart quicker than a flat face.
+- **The bot slips around lips.** Flying straight into a ledge a grain or two deep, it slides past
+  instead of stopping dead. A real wall still stops it.
+- **Tuned pulses** do none of this; they only touch the tuned material.
+
+Upgrade ideas, not built yet:
+- Amplifier: reaches deeper per pulse.
+- Tuning fork: tuning could become an upgrade instead of being there from the start.
+- Harmonics: breaks granite, then basalt (could replace the bit tiers).
+
+The owner wants the whole upgrade system redesigned. The bit mold does not really fit a
+resonance drill (see NOTES.md).
+
+## Later: Grav pick (upgrade tool)
+A gravity field locks onto a lump of rock, pries it out whole and carries it. It then crushes it
+into grains or throws it, into a hopper or a furnace.
+
+It is too slow for normal digging, but useful for selective digging and for moving material.
+Upgrades:
+- field coil: bigger lumps;
+- stabilizer: range;
+- compressor: crushes faster;
+- sling: throws.
+
+## Late game: Mining charges
+Placed charges that blast a radius and throw debris, for digging out big areas.
+
+## Concept art
+Animated concepts for both tools are on the "Dig Tool Concepts" design canvas in claude.ai (not
+in this repository).