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/08-fidelity.md

@@ -37,7 +37,7 @@ A paper has thousands of nodes, and nobody signs thousands of times, so people s
 | `doc` | Yes | The document key. |
 | `rev` | Yes | The revision reviewed. |
 | `level` | Yes | `F1`, `F2` or `F3`. |
-| `scope` | Yes | `all`, `section:<id>`, `page:<n>`, `targeted:<name>` (such as `targeted:lode`), or `qa:<receipt id>` for a spot-check. |
+| `scope` | Yes | `all`, `section:<id>`, `page:<n>`, `targeted:<name>` (such as `targeted:paperclaim`), or `qa:<receipt id>` for a spot-check. |
 | `nodes` | Yes | `[[id, node_hash], …]`, sorted by ID without repeats. |
 | `records` | No | `[[kind, id, hash], …]` for other things signed in the sitting: `annotation`, `digitization`, `correction`, `layer` or `checklist`. |
 | `root` | Yes | The Merkle root ([8.5](#85-merkle-roots)). |