feat: zipped packages, target set, checklists, audit fixes and a stress test

Features for the next six months (accessible HTML export, paperpack and
Lode on packages, the personal bundle):

- Zipped packages: the oracle writes and reads `.sct.zip` archives under
  the rules of spec/12 §12.2; validate.py and load.py accept them; a
  byte-identical zip of the tiny package joins the fixtures, and two
  broken archives (traversal, symbolic link) join fixtures/invalid.
- The target set of targeted F3 (spec/08 §8.10) is computed by the
  oracle and pinned by vectors/targets.jsonl under each digit rule; the
  rule now covers cells as well as sentences and the leaves of anchored
  containers, and defines a node's section.
- scienting-checklist/1 (provisional): a conformance check of an export,
  covered by a receipt as ["checklist", id, hash] (spec/08 §8.11), with a
  WCAG 2.1 AA fixture and its receipt.
- QA reports are signed like receipts (spec/08 §8.9).
- A `description` annotation body with role alt or long, so an
  accessible export can find a confirmed figure description; the layer
  fixture carries one, and the store's body-kind constraint allows it.
- scienting-spot-check/1, the seed payload, is registered with a schema.
- exercise, submission and grade are provisional until a course has
  used them.

Audit fixes, each with a vector or a broken package where one was
missing:

- Folder packages: symbolic links are refused on validate and load,
  manifest paths must not collide under case folding, listed files are
  matched by exact name, files are hashed in chunks under a size limit.
- Files are compared byte for byte, so CR LF, a byte order mark, NaN,
  a lone surrogate or invalid UTF-8 is refused instead of translated;
  integers beyond 2^53 are read as doubles, as canonical JSON writes them.
- Receipts: signature.key must equal by and the key must be valid when
  signed; a qa receipt's nodes must be the sample at the original's
  hashes, its scope must name qa.of, its errors must be sampled nodes;
  statuses are computed once, iteratively, so chains of spot-checks
  hundreds deep settle; Base64 and manifest shape errors become refusals
  instead of tracebacks; counts and the fidelity of roster-less packages
  are recomputed.
- The gate enforces rule 11 of spec/11 §11.4: changed nodes are
  validated against the node schema and the references between nodes
  are checked, so a set to a bad value, an insert with unknown
  properties or a delete of a referenced header cell is refused; a
  relabel to null drops the label; a reclassify drops foreign
  attributes; a split strips whitespace across runs; ids.jsonl order
  follows spec/04 §4.4 in every state; a move after itself is refused.
- Anchors: the relabel rule requires that nothing else changed below the
  node; an alias chain ending in a deletion no longer crashes resolve.
- Notation: a script after an empty group applies to the previous atom
  ({}^{14}C); letters are defined by Unicode block in spec/05 §5.4 and
  the oracle; \left) is complex.
- Page fingerprints delete whitespace before folding, so "10 -20" and
  "10-20" fold alike (spec/07 §7.1).
- Grades are summed with exact decimals; the reviewer error bound is
  computed with integer arithmetic.
- receipts and revocations are keyed by (doc_key, id) in SQL, since one
  revocation may be carried by several packages.

Checking:

- tools/stress.py: seeded randomized property tests over canonical JSON,
  normalization, notation, random correction walks, anchor resolution,
  Merkle roots, spot-check samples, error bounds, fingerprints, mutated
  archives and packages, rights and spot-check chains; CI runs it.
- check.py verifies every count and version the prose states against
  the repository, the zipped fixture and crafted archives, the checklist
  coverage, and nine more broken packages.
- CONTRIBUTING.md gains a release checklist.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

fixtures/records/layer/receipt.json

@@ -1 +1 @@
-{"at":"2026-10-11T19:30:00Z","by":"ana","doc":"hale2026harmonic","evidence":[],"format":"scienting-receipt/1","id":"fdfbqrwwd2w3w","level":"F3","nodes":[],"records":[["annotation","h6s98vg6qcyjp","3cbe10d4ecdff3089a25f1b5ca5061e02201243e1bc4ccbe68a92e34a6b18b56"],["annotation","x0abag88jjq4t","7cbc20c779f95e25b2342a316ddf68750110782c0894e00d50dc3073ed5c980e"],["annotation","xbwf8p70398mp","1b0581890cdc337c30feb66baa7691ef2a599888b3df3c348d750e4072dbabd5"],["annotation","y228zv031s285","0eccd844df132a805887437e555e05428424fafa9eb3b2644a7f49a096442a09"]],"rev":12,"root":"fda3463d979d2272c491041e39081f18d8ed2d17affe330b0b58b4fde86106fc","scope":"targeted:layer","signature":{"key":"ana","scheme":"ed25519","value":"HqFlk7RXBLAScs/ANkCPbg7N9jT4KdQ60eCig4VLmbON4ke7//dMLGeaM5DRHpjZH/IIr895eAPS4Nd6YJSPCA=="}}
+{"at":"2026-10-11T19:30:00Z","by":"ana","doc":"hale2026harmonic","evidence":[],"format":"scienting-receipt/1","id":"q1mqaaps430at","level":"F3","nodes":[],"records":[["annotation","dz7b0r84n38wp","f7a5af8530468fe4dc54dcca3f2f0cfbfe69db1a77855febdd1a2f3c69d46cfa"],["annotation","h6s98vg6qcyjp","3cbe10d4ecdff3089a25f1b5ca5061e02201243e1bc4ccbe68a92e34a6b18b56"],["annotation","x0abag88jjq4t","7cbc20c779f95e25b2342a316ddf68750110782c0894e00d50dc3073ed5c980e"],["annotation","xbwf8p70398mp","1b0581890cdc337c30feb66baa7691ef2a599888b3df3c348d750e4072dbabd5"],["annotation","y228zv031s285","0eccd844df132a805887437e555e05428424fafa9eb3b2644a7f49a096442a09"]],"rev":12,"root":"72e9d4780a5d61c54e54933e4c576d69f3f079de9901526554a2d381845e437c","scope":"targeted:layer","signature":{"key":"ana","scheme":"ed25519","value":"+foYjFFLJQDJe5a58u8eIEU9e8OCHa2YwOT2xxcwCOUhTXXIPbYGL3GrFhzi5XeftXab7AoKzs4jVNQcSrW4Bw=="}}