feat: validator, bundle builder and release checks for 0.1.0

- Add tools/validate.py: validates packages, and with --correction runs
  proposed corrections through the gate against a package without
  writing anything (spec/11 §11.4). The gate now refuses a proposal that
  fails the correction schema, rule correction.schema.
- tools/load.py validates every package before loading, and with
  --bundle --built-from builds a scienting-bundle/1 with the FTS5 search
  index and bundle_meta (spec/13 §13.5). Search rows are defined per
  unit (sentence, cell, equation outside a sentence, figure-text) with
  the parent kind as context.
- Roster keys carry a role, and a key with the role owner may revoke any
  receipt (spec/08 §8.7, spec/20); roster schema, store table and the
  fixture roster updated. The checker signs a trial revocation to prove
  the rule both ways.
- A qa: receipt raises the nodes it sampled except those in its errors
  (spec/08 §8.2); the example paper's fidelity counts become 27 F3,
  13 F2, 4 F1 and 1 F0.
- The destination chooses the keyed scheme, not the text policy:
  hmac-team between the team's machines, hkdf-pages outside the team
  (spec/05 §5.8, spec/12 §12.5).
- A TextQuoteSelector must repeat the anchor's plain quote and is absent
  for hashed or keyed anchors (spec/18 §18.3).
- Add fixtures/records/suspect.json, a scienting-suspect/1 record.
- Oracle: hashes are kept incrementally and checked after every
  correction against a full recomputation; load and write refuse unsafe
  manifest paths; Ed25519, HKDF and schema validation come from the
  cryptography and jsonschema packages; canonical JSON uses the built-in
  encoder with an exact RFC 8785 fallback.
- The tools need Python 3.14 with cryptography and jsonschema; the py310
  CI environment is dropped and the workflow runs the default only.
- Resolve every [CHECK] note in the docs, READMEs and context; add
  CONTRIBUTING.md; every tool answers --help and refuses unknown options.

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

CONTRIBUTING.md

@@ -0,0 +1,46 @@
+# Contributing
+
+This page is for anyone who wants to fix the specification, change a format or add an example.
+Propose a change as a pull request on the repository at <https://git.scient.ing/infra/manuspec>.
+
+## What a change needs
+
+A change starts in the chapter of [the specification](spec/README.md) that defines the rule, because the chapters are normative.
+The schemas, SQL, registries, vectors and fixtures then follow the chapter ([spec/00 §0.5](spec/00-introduction.md#05-how-the-repository-is-arranged)).
+
+1. **Change the chapter.**
+   Say what is new in the chapter's own terms, and link the sections it touches.
+2. **Change the schemas, SQL and registries** that the rule shapes.
+   A new refusal gets a rule ID in [registry/rules.json](registry/rules.json).
+3. **Compute, never type, the expected values.**
+   Change the oracle in [tools/oracle/](tools/oracle/) to apply the rule, and add the case that shows it to [tools/build.py](tools/build.py): a vector, a fixture or a broken package in `fixtures/invalid/`.
+   Then run `pixi run build`, which rewrites `fixtures/` and `vectors/`.
+4. **Run the checks.**
+   `pixi run check` must end with `All checks pass.`
+   Without pixi, run `python3 tools/check.py`, with Python 3.14 and two packages, `jsonschema` and `cryptography` installed.
+5. **Record the change** in [CHANGELOG.md](CHANGELOG.md).
+
+## Versions
+
+A change that makes a valid file invalid, or that changes a computed value, is a breaking change and needs a new major version of the format, with a migration.
+Adding an optional property, a node kind, a run kind or an enumeration value is a minor change ([spec/00 §0.3](spec/00-introduction.md#03-format-identifiers-and-versions)).
+A rebuild that changes any file under `vectors/` or any hash in `fixtures/` is a computed value changing, so say in the pull request why it must.
+
+## New node kinds and run kinds
+
+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)).
+
+## Writing
+
+The checker enforces two rules on every Markdown file: one sentence per line, and US spelling.
+`pixi run lint` runs markdownlint with the repository's settings.
+Define each term where it first appears, because the guides and READMEs are written for newcomers as well as implementers.
+
+All fixture text is synthetic, written for the fixtures.
+The keys in `fixtures/keys/` are public test keys and must never sign anything else.
+
+## Licenses
+
+Each path keeps the license that [LICENSE.md](LICENSE.md) gives it: prose CC-BY-4.0, the normative data CC0-1.0, and `tools/` Apache-2.0.