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>

docs/concepts.md

@@ -260,7 +260,7 @@ Every leaf has a level that says how far its text was checked.
 
 A level counts only at the node's current hash, so a correction drops a proofread sentence back until someone signs for it again.
 The pipeline records F0, F1 or F2; F3 comes only from a valid receipt.
-The example reports 28 leaves at F3, 12 at F2, 4 at F1 and 1 at F0, which is its 45 leaves.
+The example reports 27 leaves at F3, 13 at F2, 4 at F1 and 1 at F0, which is its 45 leaves.
 See [chapter 8](../spec/08-fidelity.md).
 
 ## Receipts and spot-checks
@@ -307,9 +307,9 @@ A keyed hash (an HMAC) needs a secret key to compute, so guessing does not work
 
 Values are plain SHA-256 inside the team.
 Exported to another of the team's machines, they are HMACs under the team's key.
-In a public layer, the key is derived from the paper's page fingerprints (see the previous section), so only someone holding the paper can check them. [fixtures/packages/hale2026harmonic.checks-only](../fixtures/packages/hale2026harmonic.checks-only) is the example paper exported this way, under the team key.
-
-[CHECK: spec/05 §5.8 lists the page-derived key for "any export on a work whose text is withheld", but spec/12 §12.5, fixtures/README.md and the checks-only fixture's document.json use the team key (hmac-team); confirm which the spec intends before stage 03]
+In a public layer, or in an export outside the team, the key is derived from the paper's page fingerprints (see the previous section), so only someone holding the paper can check them.
+Where the values go chooses the key, not whether the text is withheld.
+[fixtures/packages/hale2026harmonic.checks-only](../fixtures/packages/hale2026harmonic.checks-only) is the example paper exported to another of the team's machines, so it uses the team key.
 
 A checks-only package also has no corrections, suspects or datasets.
 Pinned by [vectors/keyed.jsonl](../vectors/keyed.jsonl).