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.

references/api.md

@@ -0,0 +1,14 @@
+# Notes macros
+
+Defined in `assets/notes-macros.tex` (loaded by `assets/notes-template.tex`).
+
+| macro | args |
+|---|---|
+| `\splabel{C1}` | hypertarget + label |
+| `\spref{C1}` | clickable id |
+| `\spsource{§3.2}` | source footnote |
+| `\spfig[w]{F1}{caption}{provenance}` | `figures/F1/build/F1.pdf` |
+| `\spscreenshot[w]{F2}{caption}{provenance}` | `figures/F2/orig.png` |
+| `quotebox` | short quotation |
+
+Scripts: `ingest.sh`, `lint.py`, `render_ledger.py`, `build.sh`, `screenshot.sh` all take `--work`.