docs: job-DAG queue model; fold agent_power table into broker.sqlite

coordinator.md rewrites the queue section (node inventory, DAG shapes,
resources, desired-state reconciliation, boot reconcile); approvals.md
+ persistence.md + hivectl --graceful help updated to match. agent_power
lives in broker.sqlite like approvals/questions (own connection + busy
timeout) instead of a separate db file.

docs/persistence.md

@@ -2,12 +2,12 @@
 
 Where state lives, what survives what, and how it's bounded.
 
-## Three sqlite databases
+## Sqlite databases
 
 ### `/var/lib/hyperhive/db/broker.sqlite` (host)
 
-Six tables, all in one file — four queues plus the schedule
-header/targets split:
+Seven tables, all in one file — four queues, the schedule
+header/targets split, and the per-agent power-intent registry:
 
 - `messages` — every inter-agent / operator-bound message.
   `sender / recipient / body / sent_at / delivered_at / acked_at /
@@ -44,6 +44,17 @@ header/targets split:
   last_fired_at_unix / last_result`. `ON DELETE CASCADE` from
   `scheduled_prompts(id)` — requires `PRAGMA foreign_keys = ON`
   per connection (set at open).
+- `agent_power` — one tiny row per agent: `agent PK / wanted (up |
+  offline) / updated_at` — the durable power *intent* behind the job
+  queue's desired-state reconciliation
+  (`docs/coordinator.md::Job queue`; owner: `hive-c0re/src/power.rs`).
+  Written synchronously by every operator/agent power action
+  (dashboard start/stop, `hivectl stop`, the MCP kill/start tools,
+  spawn approval); read by `Reconcile` nodes and the boot reconcile.
+  Intent survives hive-c0re restarts — in-flight queue work
+  deliberately does not. Agents without a row are seeded from
+  observed state on first touch (running ⇒ `up`); destroy deletes
+  the row.
 
 Retention:
 
@@ -63,6 +74,8 @@ Retention:
   (`cancel_schedule` MCP / dashboard ✗) which tombstones via
   `cancelled_at_unix`, then `reap_cancelled` drops the row on
   the next worker pass.
+- `agent_power` rows live until the agent is destroyed (one row per
+  agent — nothing to vacuum).
 
 ### `/harness/hyperhive-events.sqlite` (per agent)