Finish CUST-WP-0011 and implement STATE-WP-0061 suggestion backlog.

Add persisted Suggestion entities with WSJF ranking, relevance bumps,
REST/MCP write surfaces, /suggestions dashboard page, and daily triage
digest integration. Document the cluster operating model, archive the
completed migration workplan, and seed WARDEN-WP-0012 routing scenarios.

dashboard/src/docs/capabilities.md

@@ -227,5 +227,8 @@ and age in days.
 ---
 
 *Capability requests are a sanctioned write use case of the State Hub alongside
-`resolve_decision` and `get_next_steps`. They do not originate in workplan files —
+`resolve_decision`, `get_next_steps`, and the suggestion backlog writes
+(`create_suggestion`, `vet_suggestion`, `decline_suggestion`,
+`promote_suggestion_to_task`, `bump_suggestion_relevance`). They do not
+originate in workplan files —
 they are operational coordination.*

dashboard/src/docs/suggestions.md

@@ -0,0 +1,49 @@
+# Demand-Weighted Suggestion Backlog
+
+The `/suggestions` page shows persisted **gated needs** that are not yet real
+tasks. Each unmet lookup increments `relevance`, which raises WSJF ranking.
+
+## Stages
+
+| Stage | Meaning |
+|-------|---------|
+| `suggestion` | Recorded need, not yet vetted |
+| `requirement` | Vetted with structured fields and notes |
+| `promoted` | Became a real `Task` (`promoted_task_id` set) |
+| `declined` | Rejected; terminal |
+
+## WSJF projection
+
+```text
+cost_of_delay = base_value + (relevance_weight × relevance)
+wsjf = cost_of_delay / job_size
+```
+
+`GET /suggestions?rank=wsjf` returns open suggestions/requirements ordered by
+score. Promoted and declined entries are excluded unless
+`include_terminal=true`.
+
+## Sanctioned writes
+
+MCP and REST:
+
+- `create_suggestion` / `POST /suggestions/`
+- `vet_suggestion` / `POST /suggestions/{id}/vet`
+- `decline_suggestion` / `POST /suggestions/{id}/decline`
+- `promote_suggestion_to_task` / `POST /suggestions/{id}/promote`
+- `bump_suggestion_relevance` / `POST /suggestions/{id}/bump-relevance`
+
+Relevance also bumps automatically when:
+
+- `GET /state/next_steps` surfaces open suggestions
+- A `CapabilityRequest` matches an open suggestion
+
+## Daily triage
+
+`GET /state/summary` includes `ranked_suggestions` for the activity-core
+`daily_triage_digest` resolver. See [WSJF Triage](/docs/wsjf-triage).
+
+## Origin
+
+Motivated by ops-warden `WARDEN-WP-0012` gated routing scenarios. Example
+backfill: `scripts/seed_wp0012_suggestions.py`.