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

fixtures/records/log/checkpoint

@@ -1,6 +1,6 @@
 scient.ing/log/smithlab
 9
-Ga0n103p3Gl136z6XWmM92kGvsvMYGXlk+ijjX4KWiA=
+WQxnIeoDxqOJ/rIz5b0uJ3pfpq4S1kUQMNvbG55bPEM=
 
-— ana dBv7wtCAdNnczkCO5KwtrmDvtWUVPRusBSuLPeBDQoLZi9Hm34IHuNjvnjyPEar5afNf7xqcDtokk2XZEP31uJMVuwE=
-— wit h7ghDsJGkhWLaPO7+TIZQUenslhiQh/E/TKWU4ddphpFcuylQBZM2kG/o8H1nyPfUT0MkbvnFqPFfHPH3OaN5W1EwAI=
+— ana dBv7wrLxQN8XFJOwKZO4L98UosXwyw3jVbYTM3a+dZWQdtZkPqd6fM8LHwgbIyBT+OEq18meE0JkqJKoYeZ2DMP7eAo=
+— wit h7ghDsbQuWAI5VIGw+jiEAMHeSpDVlubOR46YIEuxL5TWkxU1xAtrp4gwgKxCV+q72A9mZC6APgyaCAUi78euiV/SA8=