refactor!: claim references are claim:TAG

lode is renamed paperclaim. A claim reference is claim:TAG or
claim:host/TAG and a pin claim:TAG@hex6 (claimRef and claimPin in
common.schema.json, spec/18 §18.4, spec/02, spec/20); the eight-character
tags do not change. A project names its claim namespace as
claims.paperclaim, and the main example's targeted receipts take the
scope targeted:paperclaim. No old prefix or name is accepted.

paperspec build regenerated the fixtures and vectors: the claim link's and
the symbol's record IDs, the layer receipt, project.json, the two targeted
receipts and Ben's spot-check, the QA report, the inclusion proof, the log's
checkpoint and tiles, and the signature, spot-check, VRF and checkpoint
vectors. The walkthrough and examples quote the new receipt IDs.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01SarHTuHhV9cS85XWy2NrLJ

CHANGELOG.md

@@ -62,7 +62,7 @@ They are minor changes too: new operations, enumeration values and optional prop
 - The rules `correction.emend`, `correction.relink`, `correction.resolve` and `doc.correction.resolution` are registered, the `corrections` table's CHECK takes the three operations ([sql/doc.sql](sql/doc.sql)), `corrections.State` carries the reference records, and `paperspec stress` walks the three operations with their invariants.
   `corrections.jsonl` gains thirteen cases and `projections.jsonl` and `projection-groups.jsonl` two each; no existing case changes.
 
-Four more, asked for by papermath, which defines the math form `scienting-math/1`, and by lode, the claim store whose claims and symbols layers point at.
+Four more, asked for by papermath, which defines the math form `scienting-math/1`, and by paperclaim, the claim store whose claims and symbols layers point at.
 The first two are minor changes: an optional property, a derived file and its schema, with no hash, ID or key of an existing file changed.
 The last two make some files that were valid invalid, which [spec/00](spec/00-introduction.md) calls breaking; they are made now because no release of `scienting-doc/1` or `scienting-layer/1` has been tagged, and a reference worth changing is changed before one is ([CONTRIBUTING.md](CONTRIBUTING.md#releasing), item 4).
 
@@ -76,9 +76,10 @@ The last two make some files that were valid invalid, which [spec/00](spec/00-in
   The validator now checks derived files: each line against its schema, that it names a formula of the package (`doc.derived.node`), that a math line's formula is TeX and its `complete` and `symbols` agree with its tree (`doc.derived.math`), and that a checks-only package carries none (`doc.policy.withheld`), since a tree or MathML reads the withheld text.
   The main example gains `derived/math.jsonl`, papermath 0.1.0's reading of its equation and of two math runs, copied by hand because the oracle does not implement the form; `paperspec check` validates fourteen variants of it, and no fixture's hashes change.
   There are now 43 schemas, which the 0.1.0 entry above, held to the repository by `paperspec check`, states too.
-- Claim references ([spec/18 §18.4](spec/18-layers.md#184-bodies), [spec/02 §2.4](spec/02-model.md#24-work-and-document-keys), [spec/20](spec/20-projects.md), `claimRef` and `claimPin` in `common.schema.json`): the `source` of a `claim-link` or `symbol` body, a `lode:` identifier in `same_as`, and a project's claim step are lode references, `lode:<tag>` or `lode:<host>/<tag>` with the tag eight Crockford base32 capitals, and a `pin` is the reference, `@` and six lowercase hex digits of the claim's statement hash, as lode writes them.
-  A slug such as `lode:amber/k-bond`, which lode may rename, was valid before and is not now.
-  The fixtures' `lode:amber/k-bond` and `illustrative-pin` become `lode:272XTX7C` and `lode:272XTX7C@02f47b`, the claim `amber/k-bond` of lode's example store, which changes the claim link's record ID, the layer receipt and `project.json`.
+- Claim references ([spec/18 §18.4](spec/18-layers.md#184-bodies), [spec/02 §2.4](spec/02-model.md#24-work-and-document-keys), [spec/20](spec/20-projects.md), `claimRef` and `claimPin` in `common.schema.json`): the `source` of a `claim-link` or `symbol` body, a `claim:` identifier in `same_as`, and a project's claim step are paperclaim references, `claim:<tag>` or `claim:<host>/<tag>` with the tag eight Crockford base32 capitals, and a `pin` is the reference, `@` and six lowercase hex digits of the claim's statement hash, as paperclaim writes them; a project names its claim namespace as `claims.paperclaim`.
+  A reference by slug, such as `amber/k-bond`, which paperclaim may rename, or under any other prefix, was valid before and is not now.
+  The fixtures' slug reference and `illustrative-pin` become `claim:272XTX7C` and `claim:272XTX7C@02f47b`, the claim `amber/k-bond` of paperclaim's example store, which changes the claim link's and the symbol's record IDs, the layer receipt and `project.json`.
+  The main example's two targeted receipts take the scope `targeted:paperclaim`, which changes their IDs and signatures, Ben's spot-check of the second (its seed and its sample of ten, still without errors), the QA report, the inclusion proof, the transparency log's checkpoint and tiles, and the signature, spot-check, VRF and checkpoint vectors built from them; no node's level or the report's counts change.
 - Symbol keys ([spec/18 §18.4](spec/18-layers.md#184-bodies), `annotation.schema.json`, the `key` term of the JSON-LD context, `sct:symbolKey`): a `symbol` body names its symbol by `key`, its `scienting-math/1` key, besides the span its target selects, so a symbol is found across papers and matched to its claim by key; a `symbol` body without `key` was valid before and is not now.
   The example layer gains a proposed symbol annotation on `$K_r$`, with the key `K_{r}`.
 - Three failures of `paperspec stress` with the seeds 1, 2 and 7, in code the earlier changes did not touch.