feat(STATE-WP-0079): retire the suggestion-backlog surface (slice E1)

History is archived fleet-side, so the read surface has no remaining job.

- api/routers/suggestions.py: whole prefix 410s with a pointer to intake and
  to the archive; the router drops from 176 lines to a stub
- mcp_server: the 6 suggestion tools removed outright rather than stubbed --
  a retired tool that still appears in the tool list costs every agent
  session context on every call, which is the opposite of retiring it
- write_idempotency: 5 /suggestions rules dropped
- dashboard: suggestions.md deleted, nav entry removed, reference.md and
  wsjf-triage.md updated; docs/suggestions.md rewritten as archive pointer
- tests: two tests pinned the old read-live behaviour and now pin the
  retirement contract instead

Tables stay: they are retire/archive in SHR-INV-0001 and are captured by the
final dump at T06.

Untouched, and worth knowing during cutover: ui-feedback.md / todo.md
'suggestions' are Shift+click dashboard feedback backed by technical_debt, a
different entity that shares the word. E3 (dashboard-meta) is that page; its
owner is state-hub-until-cutover so it retires at the T06 window, not now.

Full suite 612 passed.

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

docs/evidence/legacy-meter-weekly-review-20260820.json

@@ -1,12 +1,12 @@
 {
-  "captured_at": "2026-08-20T05:27:26.224218+00:00",
+  "captured_at": "2026-08-20T06:00:07.693350+00:00",
   "api_base": "http://127.0.0.1:8000",
   "workplan": "STATE-WP-0070",
   "retired_interfaces": [],
   "weekly_review": {
-    "generated_at": "2026-08-20T05:27:26.217390Z",
-    "window_start": "2026-08-13T05:27:26.168151Z",
-    "window_end": "2026-08-20T05:27:26.168151Z",
+    "generated_at": "2026-08-20T06:00:07.687814Z",
+    "window_start": "2026-08-13T06:00:07.633734Z",
+    "window_end": "2026-08-20T06:00:07.633734Z",
     "cadence": "weekly",
     "activity_core_handoff": {
       "activity_id": "statehub-legacy-interface-review",

docs/retirement-cutover-slice-plan.md

@@ -180,7 +180,7 @@ D3 is two MCP tools with no dependants; take it opportunistically.
 | --- | --- | --- | --- |
 | E1 | `suggestion-backlog` → archive | 17 | history archived 2026-08-20; read surface + dashboard remain |
 | E2 | `work-records-workplan-legacy` → archive | 13 | legacy-meter — candidate rule, see below |
-| E3 | `dashboard-meta` | 1 | none |
+| E3 | `dashboard-meta` (`/ui-feedback`) | 1 | T06 freeze window — owner is `state-hub-until-cutover` |
 | E4 | `legacy-meter` itself | 9 | **last** — it is the instrument for E2 |
 
 E4 retires only after every other legacy surface is closed; retiring the meter
@@ -197,12 +197,25 @@ live so the historical record stayed reachable.
 migration target. Every entry was `declined` in the intake migration and none
 was promoted, so nothing forward-looking is lost by removing the surface.
 
-**Remaining for E1:** retire the 8 read routes and 6 MCP tools, then drop the 3
-tables at the T06 dump. This has a dependency the inventory's 17-item count does
-not show — `dashboard/src/suggestions.md` is a live page, and `index.md` and
-`wsjf-triage.md` reference it. The dashboard must be updated in the same change
-or the retirement breaks it. Sequence E1's removal with A4/B5 (the UI slices)
-rather than ahead of them.
+**Executed 2026-08-20.** The 8 read routes now 410 with a pointer to intake and
+to the archive, the 6 MCP tools are removed (not stubbed — a retired tool that
+still appears in the tool list costs every agent session context on every call),
+the 5 `/suggestions` write-idempotency rules are gone, and the dashboard page is
+deleted with its nav entry, `reference.md` row, and `wsjf-triage.md` link
+updated. `dashboard/src/docs/suggestions.md` is rewritten as the archive
+pointer. Tables stay for the T06 dump.
+
+One naming trap worth recording: **`ui-feedback.md` and `todo.md` "suggestions"
+are a different entity** — Shift+click dashboard feedback backed by
+`technical_debt`, not the suggestion backlog. They are untouched. Anything
+grepping for `suggestion` during cutover will hit them.
+
+### E3 status (2026-08-20)
+
+`dashboard-meta` is the `/ui-feedback` page — the feedback scratch surface just
+mentioned. Its owner is `state-hub-until-cutover` and it is still in active use,
+so it retires **at the T06 freeze window**, not before. Removing it now would
+delete a working feedback loop during the retirement it serves. No action.
 
 ### E2 evidence — defect found and partly fixed (2026-08-20)