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

build.py

@@ -0,0 +1,56 @@
+#!/usr/bin/env python3
+"""Build Deepgrain Foundry into one self-contained HTML file.
+
+The source files listed in src/manifest.json are joined in order (sim first, then the browser
+code) into one classic script, so they share one global scope and 'use strict' at the top of
+src/sim/base.js applies to all of it. No bundler, no dependencies.
+
+Writes:
+  dist/index.html             the full page: open it, or serve dist/ with python -m http.server
+  dist/deepgrain-foundry.html the same without <!doctype>/<head>/<body>, for hosts (like a
+                              claude.ai artifact) that wrap the page themselves
+  dist/bundle-lines.json      where each source file starts in dist/index.html, so a line number
+                              from a browser error can be traced back: python3 tools/where.py LINE
+"""
+import json, pathlib
+
+root = pathlib.Path(__file__).resolve().parent
+src = root / 'src'
+dist = root / 'dist'
+man = json.loads((src / 'manifest.json').read_text())
+
+
+def join(files):
+    """Join files with one newline between them; return the text and [first line, file] pairs."""
+    parts, starts, line = [], [], 1
+    for f in files:
+        text = (src / f).read_text().rstrip('\n')
+        starts.append([line, f])
+        parts.append(text)
+        line += text.count('\n') + 1
+    return '\n'.join(parts), starts
+
+
+def main():
+    shell = (src / man['shell']).read_text()
+    css, _ = join(man['css'])
+    js, starts = join(man['sim'] + man['client'])
+    head, tail = shell.split('//__JS__')
+    body = head.replace('/*__CSS__*/', css)
+    page = body + js + tail
+    pre = ('<!doctype html><html><head><meta charset="utf-8">'
+           '<meta name="viewport" content="width=device-width,initial-scale=1,viewport-fit=cover">'
+           '</head><body>')
+    full = pre + page + '</body></html>\n'
+    dist.mkdir(exist_ok=True)
+    (dist / 'deepgrain-foundry.html').write_text(page)
+    (dist / 'index.html').write_text(full)
+    # the script starts on this line of index.html (the doctype prefix has no newlines)
+    js_line = body.count('\n') + 1
+    (dist / 'bundle-lines.json').write_text(json.dumps(
+        {'page': 'dist/index.html', 'files': [[js_line + s - 1, f] for s, f in starts]}, indent=1) + '\n')
+    print(f'built dist/index.html ({len(full):,} bytes, {len(starts)} source files)')
+
+
+if __name__ == '__main__':
+    main()