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-0043-state-hub-repo-extraction.md

@@ -107,7 +107,7 @@ should become authoritative in `/home/worsch/state-hub`:
 | `infra/` | Move; local Postgres compose and infra docs. |
 | `mcp_server/` | Move; MCP server and tool reference. |
 | `migrations/` | Move; Alembic migration environment and versions. |
-| `policies/` | Move; repo DoI and workstream DoD policies. |
+| `policies/` | Move; repo DoI and workplan DoD policies. |
 | `prompts/` | Move; State Hub prompt assets. |
 | `pyproject.toml` | Move; Python package/dependency definition. |
 | `scripts/` | Move; consistency, registration, SBOM, token, image, and repo-sync tooling. |
@@ -271,7 +271,7 @@ Connect `/home/worsch/state-hub` to State Hub as a managed repo in the
 
 Use the file-first rule for repo-backed workplans. If new workplan files are
 created in the standalone repo, write them before running consistency sync or
-registration tooling so no ghost workstreams are created.
+registration tooling so no ghost workplans are created.
 
 Done when State Hub repo metadata resolves the local host path for
 `/home/worsch/state-hub`, and `fix-consistency --here` or the equivalent repo
@@ -291,13 +291,13 @@ registered. The first priority is the recently generated
 `CUST-WP-0042 - Workplan State Model Cleanup`.
 
 The migration should preserve existing State Hub IDs where appropriate and avoid
-creating duplicate workstreams. If the consistency engine cannot safely move an
-existing file-backed workstream across repos, record the limitation and use the
+creating duplicate workplans. If the consistency engine cannot safely move an
+existing file-backed workplan across repos, record the limitation and use the
 least confusing transition path:
 
 - keep the old file as an archived pointer, or
 - create a new State Hub-local continuation plan that references the old
-  workstream explicitly
+  workplan explicitly
 
 Done when future agents can work on the State Hub state-model cleanup from the
 standalone repo without editing `the-custodian/state-hub/`.
@@ -360,7 +360,7 @@ After extraction is verified, resume `CUST-WP-0042` from the standalone
 
 - confirm the workplan paths point at the new repo layout
 - confirm `state_hub_workstream_id` and task IDs still refer to the intended
-  workstream/tasks
+  workplan/tasks
 - update any acceptance criteria that assumed the embedded path
 - record a progress event linking this extraction workplan to the resumed
   state-model cleanup work
@@ -385,7 +385,7 @@ complete, because its changes should land in the standalone `state-hub` repo.
 - `the-custodian` no longer owns a live copy of State Hub implementation code.
 - State Hub repo metadata knows the standalone repo path on this host.
 - New State Hub workplans can be synced from the standalone repo without ghost
-  workstreams.
+  workplans.
 - Existing active State Hub work, especially `CUST-WP-0042`, has a clear and
   non-duplicating handoff path into the standalone repo.
 - Local API, MCP, migration, dashboard, test, and consistency workflows are