feat: land superpaper v1 notes scaffold

Add the ledger schema, class router, lint codes, ingest/build
pipeline, and three work-tree examples: align derivation,
superfig delegation, and supertensor delegation.

scripts/preflight.sh

@@ -0,0 +1,57 @@
+#!/usr/bin/env bash
+# Notes toolchain preflight. 0 = full, 1 = degraded, 2 = no LaTeX engine.
+set -uo pipefail
+
+QUIET=0
+[[ "${1:-}" == "--quiet" ]] && QUIET=1
+say() { [[ $QUIET -eq 1 ]] || echo -e "$*"; }
+
+ROOT="$(cd "$(dirname "${BASH_SOURCE[0]}")/.." && pwd)"
+ok=0; warn=0; fail=0
+check() {
+  local name="$1"; shift
+  if "$@" >/dev/null 2>&1; then say "  ok    $name"; ok=$((ok+1)); return 0
+  else say "  MISS  $name"; return 1; fi
+}
+
+say "superpaper preflight"
+say "--- engine ---"
+check "xelatex"        command -v xelatex        || fail=$((fail+1))
+check "article.cls"    kpsewhich article.cls     || fail=$((fail+1))
+
+say "--- template / CJK ---"
+cjk=0
+for pkg in ctex.sty FandolSong-Regular.otf amsmath.sty amssymb.sty \
+           tcolorbox.sty graphicx.sty hyperref.sty geometry.sty \
+           listings.sty booktabs.sty subcaption.sty float.sty tikz.sty etoolbox.sty; do
+  check "$pkg" kpsewhich "$pkg" || { warn=$((warn+1)); cjk=1; }
+done
+
+say "--- python ---"
+PY="$ROOT/scripts/python"
+check "python3" command -v python3 || warn=$((warn+1))
+check "PyYAML" "$PY" -c "import yaml" || warn=$((warn+1))
+check "jsonschema" "$PY" -c "import jsonschema" || warn=$((warn+1))
+
+say "--- ingest ---"
+check "pdftotext" command -v pdftotext || warn=$((warn+1))
+check "pdftoppm"  command -v pdftoppm  || warn=$((warn+1))
+
+say "--- optional ---"
+check "magick"     command -v magick     || true
+check "pdftocairo" command -v pdftocairo || true
+
+if [[ $fail -gt 0 ]]; then
+  say ""
+  say "RESULT: no LaTeX. Deliver ledger + Markdown; no PDF."
+  exit 2
+fi
+if [[ $warn -gt 0 ]]; then
+  say ""
+  say "RESULT: degraded."
+  [[ $cjk -eq 1 ]] && say "  - missing CJK/template package -> English notes or later Missing character."
+  exit 1
+fi
+say ""
+say "RESULT: full notes path (XeLaTeX + CJK + lint)."
+exit 0