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

spec/18-layers.md

@@ -58,9 +58,9 @@ Replies are annotations that target annotations, so discussions are threads anch
 
 A textual body has a `value`, and optionally a `format` (`text/plain` or `text/markdown`) and a `language`.
 
-The `source` of a `claim-link` or `symbol` body is a claim in a lode claim store, written as lode writes a reference: `lode:` and the claim's tag, eight Crockford base32 capitals (the digits and the letters without I, L, O and U), as in `lode:272XTX7C`, or `lode:<host>/<tag>` for a claim in another store, `<host>` being a domain name.
+The `source` of a `claim-link` or `symbol` body is a claim in a paperclaim claim store, written as paperclaim writes a reference: `claim:` and the claim's tag, eight Crockford base32 capitals (the digits and the letters without I, L, O and U), as in `claim:272XTX7C`, or `claim:<host>/<tag>` for a claim in another store, `<host>` being a domain name.
 A tag never changes, while a claim's slug, such as `amber/k-bond`, may be renamed, so a slug is never a reference.
-The optional `pin` fixes the claim as the annotator read it: the same reference, `@`, and the first six lowercase hex digits of the claim's statement hash, as in `lode:272XTX7C@02f47b`.
+The optional `pin` fixes the claim as the annotator read it: the same reference, `@`, and the first six lowercase hex digits of the claim's statement hash, as in `claim:272XTX7C@02f47b`.
 `common.schema.json` defines both, as `claimRef` and `claimPin`.
 
 A `symbol` body names its symbol twice, as the target's span and by `key`, the symbol's key in the math form `scienting-math/1` ([9.4](09-figures-tables-equations.md#94-the-math-form)), which a claim store gives the symbol a symbol claim defines: `K_{r}` for a span `$K_r$`.
@@ -86,4 +86,4 @@ The store's `annotations` table keeps the category beside the body's kind ([13.4
 Nothing a model writes is ever stored as source text.
 A model may propose a `description`, and like any annotation it stays `proposed` until a person confirms it; an accessible export uses confirmed descriptions only, and a figure with none has no description.
 Other text a model writes about a span, such as a summary, is a `generated` annotation, which names its `generator`.
-`fixtures/records/layer/` holds a layer with one annotation of each common kind, each comment, caveat and question with its category, a claim link and a symbol that reference a lode claim and pin it, and the receipt that confirms some of them.
+`fixtures/records/layer/` holds a layer with one annotation of each common kind, each comment, caveat and question with its category, a claim link and a symbol that reference a paperclaim claim and pin it, and the receipt that confirms some of them.