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>

CONTRIBUTING.md

@@ -32,6 +32,19 @@ Propose a kind with the vector or fixture that shows it.
 A node kind needs its row in [chapter 3](spec/03-nodes.md), the node schema, and its entry in the `CHILDREN` table of `tools/oracle/model.py`.
 A run kind needs its row in [section 3.5](spec/03-nodes.md#35-inline-runs) and the node schema, and its text in the plain projection ([3.6](spec/03-nodes.md#36-the-plain-projection)) and in the strict and lossy projections ([5.3](spec/05-hashes.md#53-the-strict-projection), [5.5](spec/05-hashes.md#55-the-lossy-projection)).
 
+## Releasing
+
+A release is a tag on `main` whose version is the top heading of [CHANGELOG.md](CHANGELOG.md).
+Before tagging:
+
+1. `pixi run check` passes on Linux and macOS, which the workflow in `.gitea/workflows/` runs on every push.
+   The check also confirms that every count the prose states (formats, schemas, vectors, broken packages) matches the repository, and that `pixi.toml`, the registries and `tools/build.py` state the same version.
+2. `python3 tools/stress.py` passes with its default seed, and with one or two others.
+3. The JSON-LD context is served at `https://scient.ing/ns/scienting/1.jsonld` and every schema at its `$id` under `https://scient.ing/ns/schemas/`, both as static files; [context/README.md](context/README.md) records whether they resolved last time someone checked.
+   Layers claim to be W3C Web Annotations, and a JSON-LD processor that cannot fetch the context cannot read them.
+4. The decisions that freeze on release are made: enumeration values and format identifiers never change meaning afterwards ([spec/22 §22.5](spec/22-conformance.md#225-stability)), so a name worth changing is changed now.
+5. The CHANGELOG entry describes the release in the terms of the chapters it touches.
+
 ## Writing
 
 The checker enforces two rules on every Markdown file: one sentence per line, and US spelling.