fix(workplans): qualify ad-hoc identifiers with the repository prefix

`ADHOC-YYYY-MM-DD` is unique per date but not per repository, so any two repos
opening an ad-hoc on the same day collide. The 2026-08-26 fleet projection
reset refused 9 records for exactly this reason.

Canon (work-record-types_v0.1, CUST-WP-0066) settled the form as
`{PREFIX}-WP-ADHOC-YYYY-MM-DD`, filename unchanged, and grandfathered existing
ids on the condition they are never *silently* re-derived. This is the explicit
migration that clause allows for.

The hub id is derived from the record id, so a changed id is a different
record: stale state_hub_*_id fields are dropped and fix-consistency re-derives.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

Assistant: claude-code
Assistant-Model: opus
Assistant-Process: 2583210@bnt-lap001
Assistant-Session: f2bff2d5-e9b2-4338-92ca-10282a927006

workplans/ADHOC-2026-08-20.md

@@ -1,5 +1,5 @@
 ---
-id: ADHOC-2026-08-20
+id: ACTIVITY-WP-ADHOC-2026-08-20
 type: workplan
 title: "Ad hoc — activity-core opportunistic fixes 2026-08-20"
 domain: infotech
@@ -9,18 +9,16 @@ owner: codex
 topic_slug: activity-core
 created: "2026-08-20"
 updated: "2026-08-20"
-state_hub_workstream_id: "0f803d0d-cfba-5139-a476-3d0e54256daa"
 ---
 
-# ADHOC-2026-08-20 — activity-core opportunistic fixes
+# ACTIVITY-WP-ADHOC-2026-08-20 — activity-core opportunistic fixes
 
 ## Reconcile the daily TODO review sink warning
 
 ```task
-id: ADHOC-2026-08-20-T01
+id: ACTIVITY-WP-ADHOC-2026-08-20-T01
 status: done
 priority: low
-state_hub_task_id: "570d53c0-055b-54bb-ae07-17a3230f6bd1"
 ```
 
 The projected `daily-todo-md-stale-review` definition still said that