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/20-projects.md

@@ -7,9 +7,9 @@ A project, `scienting-project/1`, is the unit a team works in.
 | `key`, `store`, `name`, `description` | Its identity. |
 | `members` | People with a `role` (`owner`, `editor`, `reader` or `guest`) and the roster keys they sign with. |
 | `documents` | The project's documents, each with the `reason` it is included, `tags`, and a reading `status` per member: `unread`, `reading` or `read`. |
-| `paths` | Reading paths: ordered steps through documents, nodes, claims and layers, for onboarding a student or preparing a reading group; a claim step's `ref` is a claim reference, `lode:<tag>` ([18.4](18-layers.md#184-bodies)). |
+| `paths` | Reading paths: ordered steps through documents, nodes, claims and layers, for onboarding a student or preparing a reading group; a claim step's `ref` is a claim reference, `claim:<tag>` ([18.4](18-layers.md#184-bodies)). |
 | `layers`, `datasets`, `views`, `drafts` | What the project holds. |
-| `claims` | The claim namespace or bundle it uses, as the `lode` setting. |
+| `claims` | The claim namespace or bundle it uses, as the `paperclaim` setting. |
 | `settings` | The digit rule for targeted F3 ([8.10](08-fidelity.md#810-targeted-f3)), the drift threshold ([6.6](06-anchors.md#66-drift)), the spot-check rate and minimum ([8.8](08-fidelity.md#88-spot-checks)), what happens when a right is unknown (`refuse`, the default, or `warn`), the stage requirements in use, as the `id` of their stage file ([14](14-rights.md)), and the project's transparency `log`: its `origin`, the roster keys that `witness` it, and the `threshold` of witnesses a checkpoint needs ([23](23-log.md)). |
 
 Projects are small on purpose: everything about them is designed for hundreds of documents, not millions.