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.

tests/ledger-valid.yaml

@@ -0,0 +1,20 @@
+schema: superpaper.ledger/v1
+retired_ids: []
+paper:
+  id: toy
+  title: Toy
+  source: {kind: excerpt}
+coverage:
+  mode: excerpt
+questions: []
+claims:
+  - {id: C1, text: core claim, kind: contribution, status: core}
+definitions: []
+assumptions: []
+lemmas: []
+symbols: []
+derivations: []
+figures: []
+evidence: []
+terms: []
+source_assets: []