feat(terminology): prose sweep tool and custodian workplan cleanup (CUST-WP-0055 T04)

Add sweep_workstream_prose.py for agent-guidance files, sweep active workplan
prose in-repo, tighten scan allowlist exclusions, and update ADR-001 closure
protocol to workplan-first terminology.

docs/infrastructure-stabilization-pickup-checkpoint.md

@@ -97,9 +97,9 @@ in the relevant row and continue from its task state.
 
 ## Registration State
 
-State Hub active workstreams queried on 2026-06-27:
+State Hub active workplans queried on 2026-06-27:
 
-| Workstream | Current pickup meaning |
+| Workplan | Current pickup meaning |
 | --- | --- |
 | `artifact-store-wp-0007` | Start D7.1/D7.2 assessment and compatibility harness; D7.3 STS vending may route to NetKingdom. |
 | `ihub-wp-0022` | Ops-hub evidence intake contract is aligned to live vocabulary; runtime key custody, protected widget lookup, and smoke remain. |
@@ -119,7 +119,7 @@ State Hub active workstreams queried on 2026-06-27:
 Hygiene status:
 
 - `CUST-WP-0045-cutover-runbook` is no longer active; it is a finished runbook
-  record, not an empty active workstream.
+  record, not an empty active workplan.
 - `CUST-WP-0014` is reopened as `backlog`; it is no longer a done workplan with
   todo task blocks.
 - Completed or cancelled tasks no longer carry the stale human-needed flags
@@ -127,7 +127,7 @@ Hygiene status:
 - `make fix-consistency REPO=the-custodian` still reports pre-existing C-12
   orphan-row warnings, but the relevant workplan lifecycle and task states sync.
 - `RAIL-BS-WP-0006-staged-promotion-lifecycle` is finished: all seven tasks
-  are done, the workstream is finished in State Hub, and the file frontmatter
+  are done, the workplan is finished in State Hub, and the file frontmatter
   is `status: finished`.
 
 ## Blocker Board