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.

workplans/CUST-WP-0051-infrastructure-stabilization-metaplan.md

@@ -34,9 +34,9 @@ for removing cross-workplan blocks and creating a reliable handoff point.
 
 Reviewed on 2026-06-27 from State Hub and the repo workplan files.
 
-Active registered workstreams with open work:
+Active registered workplans with open work:
 
-| Workstream | Open state | Main stabilization meaning |
+| Workplan | Open state | Main stabilization meaning |
 | --- | --- | --- |
 | artifact-store-wp-0007 | 5 todo | Object-store compatibility and STS credential vending lane. |
 | ihub-wp-0022 | 3 wait, 5 done | Ops-hub evidence intake waits on widget seed/runtime key/smoke. |
@@ -46,7 +46,7 @@ Active registered workstreams with open work:
 | three-phoenix-ha-cluster | 7 todo | Target HA substrate is planned but not executed. |
 | staged-promotion-lifecycle | finished, 7 done | Promotion discipline ready for broad production cutovers. |
 | rail-ho-wp-0005 | 11 todo, 1 progress | Forgejo production migration needs human design and cutover decisions. |
-| cust-wp-0045-cutover-runbook | 0 tasks | Registered runbook is appearing as an active no-task workstream. |
+| cust-wp-0045-cutover-runbook | 0 tasks | Registered runbook is appearing as an active no-task workplan. |
 | net-wp-0020 | 2 wait, 1 todo, 2 done | OpenBao unseal custody models still need operator profile decisions. |
 | issue-wp-0003 | 2 progress, 5 done | issue-core deploy is close; finish live wiring and runbook evidence. |
 | activity-wp-0006 | 1 wait, 1 todo, 6 done | Three-run calibration waits on the daily-triage live gate. |
@@ -124,21 +124,21 @@ Clean up the planning substrate before execution work resumes.
 Minimum scope:
 
 - Decide whether `CUST-WP-0045-cutover-runbook` should stay registered as an
-  active workstream or be represented only as a runbook under `CUST-WP-0045`.
+  active workplan or be represented only as a runbook under `CUST-WP-0045`.
 - Resolve `CUST-WP-0014`: archive as superseded, or reopen and re-scope the six
   remaining State Hub sync-health tasks.
 - Clear or annotate stale `needs_human` flags on done/cancel tasks after source
   workplans confirm they are no longer live gates.
 - Run State Hub consistency after file changes.
 
-Done when the active workstream list no longer contains no-task runbooks or
+Done when the active workplan list no longer contains no-task runbooks or
 contradictory done-with-todo files, and the human-needed view shows only live
 human gates.
 
 Progress 2026-06-27:
 
 - `CUST-WP-0045-cutover-runbook` now has `status: finished`; State Hub no
-  longer lists it as an active workstream.
+  longer lists it as an active workplan.
 - `CUST-WP-0014` is reopened as `backlog` with its task detail preserved, so it
   is no longer a contradictory done-with-todo file or an active queue item.
 - `make fix-consistency REPO=the-custodian` passed with pre-existing C-12
@@ -357,7 +357,7 @@ priority: medium
 state_hub_task_id: "2083f0e4-e037-48bf-8069-f31e8db2fd95"
 ```
 
-Move near-complete service workstreams to done before starting larger migrations.
+Move near-complete service workplans to done before starting larger migrations.
 
 Priority order:
 
@@ -488,7 +488,7 @@ Progress 2026-06-27 staged promotion T07 and finish:
   deploy/observe plans, Stage 3 promote/rollback plans, and blocked apply paths
   for missing approval/Helm/revision evidence.
 - Marked `RAIL-BS-WP-0006` `status: finished`; `make fix-consistency
-  REPO=railiance-cluster` synced the finished workstream with only pre-existing
+  REPO=railiance-cluster` synced the finished workplan with only pre-existing
   C-12 orphan-row warnings.
 
 Progress 2026-06-30 policy-gate support closeout:
@@ -714,7 +714,7 @@ Close this metaplan by creating an operator-friendly checkpoint.
 
 Minimum contents:
 
-- active workstream list with zero stale runbooks and zero contradictory task
+- active workplan list with zero stale runbooks and zero contradictory task
   states;
 - blocker board showing no unowned credential, access, or approval gates;
 - daily automation evidence from the latest successful scheduled run;
@@ -728,7 +728,7 @@ workplan without reconstructing this review.
 
 Completed 2026-06-27: added
 `docs/infrastructure-stabilization-pickup-checkpoint.md` with the live active
-workstream list, named blocker board, latest daily-triage evidence, production
+workplan list, named blocker board, latest daily-triage evidence, production
 service status summary, and next-pick sequence. This closes the handoff surface
 for future agents while the child workplans remain the execution source of
 truth.