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-2026-06-04.md

@@ -1,5 +1,5 @@
 ---
-id: ADHOC-2026-06-04
+id: STATE-WP-ADHOC-2026-06-04
 type: workplan
 title: "Ad hoc fixes - 2026-06-04"
 domain: custodian
@@ -9,7 +9,6 @@ owner: codex
 topic_slug: custodian
 created: "2026-06-04"
 updated: "2026-06-04"
-state_hub_workstream_id: "2a8f3aff-8f5d-4e42-b33f-225d60e0b30b"
 ---
 
 # Ad hoc fixes - 2026-06-04
@@ -17,10 +16,9 @@ state_hub_workstream_id: "2a8f3aff-8f5d-4e42-b33f-225d60e0b30b"
 ## Fix Dashboard Overview API Loading
 
 ```task
-id: ADHOC-2026-06-04-T01
+id: STATE-WP-ADHOC-2026-06-04-T01
 status: done
 priority: high
-state_hub_task_id: "5f6aa1e4-ccc5-4c8b-8183-cc1578190b7b"
 ```
 
 The overview page reported `Dashboard data load failed: NetworkError when