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>

spec/05-hashes.md

@@ -170,8 +170,11 @@ So every content value that leaves a team's store is keyed.
 | Where the value goes | `hashing` | Key |
 | --- | --- | --- |
 | The team's own store and bundles | `{"scheme": "plain"}` | None. |
-| An export to another machine of the team | `{"scheme": "hmac-team", "key_id": …}` | The team key. |
-| A public layer, or any export on a work whose text is withheld | `{"scheme": "hkdf-pages", "context": …, "pages": […]}` | A key derived from the witness's page fingerprints. |
+| An export to another machine of the team, whatever its text policy | `{"scheme": "hmac-team", "key_id": …}` | The team key. |
+| A public layer, or an export outside the team on a work whose text is withheld | `{"scheme": "hkdf-pages", "context": …, "pages": […]}` | A key derived from the witness's page fingerprints. |
+
+The destination chooses the scheme, not the text policy.
+A checks-only package ([12.5](12-package.md#125-text-policies)) sent between the team's own machines is keyed with the team key, as `hale2026harmonic.checks-only` is; sent to anyone outside the team, it is keyed with the page key.
 
 A keyed scheme replaces SHA-256 with HMAC-SHA-256 under its key in every content value, including the Merkle construction of `node_hash`, and in `meta_hash`.