swarm: named scheduled prompts for one or more agents, fired in each agent

swarm-controller keeps every scheduled prompt (id, name, agents, body,
anchor, interval, paused) as one document under one key of a new
`schedule-definitions` KV bucket, so each change is a single
compare-and-set and a prompt exists for all of its agents or none. It
writes each agent's key of a new `agent-schedules` bucket as the prompts
naming that agent, without names or other agents, after every change and
on a one-minute reconcile pass. It is the only writer of both, behind
GET/POST /api/schedules and PATCH/DELETE /api/schedules/{id}.
`swarmctl schedule add|list|edit|pause|resume|rm` drives those routes over
the controller socket.

An agent's own queue credential is granted one more subject, the direct
get of its own key in `agent-schedules`. A KV watch is not granted: its
consumer create subject carries no key, so it would cover every agent's.

hive-agent's new schedule ticker reads that key every 10 seconds and fires
due slots as the same `schedule:<id>` todo hive-c0re's worker pushes. Fire
times are anchor + k*interval; the last fired slot per schedule id is kept
in the state db, so a body edit or list refresh never moves or refires a
slot, downtime fires the latest missed slot once, a restart refires
nothing, a one-shot fires once, and paused slots are skipped.

Refs #4914

hive-agent/src/main.rs

@@ -25,6 +25,7 @@ mod plugins;
 mod prompt;
 mod reminder_timer;
 mod reminders;
+mod schedule_timer;
 mod serve_common;
 mod state_entry_watch;
 mod stats;
@@ -479,6 +480,9 @@ fn spawn_todo_socket(
             // Same shape again: nudge (and feed an OTEL gauge) on a
             // grown CLAUDE.md instead of a grown state dir.
             tokio::spawn(claude_md_watch::run(store.clone(), todo_wake.clone()));
+            // Swarm-scheduled prompts fire as todos too, from the list the
+            // swarm keeps for this agent.
+            tokio::spawn(schedule_timer::run(store.clone(), todo_wake.clone()));
             Some(store)
         }
         Err(e) => {