fix(docgen): palette.py emitted ptr instead of pointer

palette.py generates selfhost/backend/stdlib/emit_color.ludic but its
template wrote `function color_lookup(name: ptr)`, while the committed,
correct source (and the rest of the compiler) uses `pointer` — so running
the generator rewrote the file to a drifted version. Emit `pointer`;
`python3 tools/docgen/palette.py` now leaves emit_color.ludic byte-identical.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

tools/docgen/palette.py

@@ -269,7 +269,7 @@ def emit_ludic(path):
   lines.append("# Edit the palette there and regenerate; do not hand-edit this file.")
   lines.append("# ============================================================================")
   lines.append("")
-  lines.append("function color_lookup(name: ptr) -> int {")
+  lines.append("function color_lookup(name: pointer) -> int {")
   for (nm, hexv, grp) in PALETTE:
     lines.append(f'  if (name == "{nm}") {{ return 0x{hexv:06X} }}')
   lines.append("  return -1")