hive-c0re stops owning scheduled prompts; agents lose the schedule tools

Scheduled prompts are swarm-level now (swarmctl schedule, #4936). The hive
keeps the rows it has only so the operator can copy them over.

- hive-c0re no longer fires anything: the scheduled-prompts worker is gone,
  and with it every create/edit/cancel/pause/resume/fire path (dashboard
  endpoints, agent-socket verbs, the SchedulePrompt approval kind and its
  approve handler). The store keeps open + list; GET /api/schedules stays.
- A v6 approvals migration drops schedule_prompt rows.
- Nothing submits approvals any more, so the submit path goes too:
  Approvals::submit_kind (now a test fixture), the ApprovalAdded dashboard
  event and its emitter.
- Coordinator::push_todo, whose only caller was the worker, goes, and with
  it hive_host_sock::agent_todo_socket and hive-c0re's hive-agent-sock /
  hive-sock-client deps.
- The schedules_changed dashboard event goes; nothing mutates the rows.
- Agents lose request_schedule_prompt, cancel_schedule, fire_schedule_now,
  edit_schedule and list_schedules, the `scheduling` tool group, their
  system-prompt line and their transcript formatters. `remind` is unchanged.

hive-sh4re/src/schedule.rs

@@ -1,15 +1,14 @@
-//! Scheduled-prompt row shape on the wire, shared by the dashboard and
-//! agent surfaces (mirrors `hive-c0re`'s internal `scheduled_prompts::Schedule`).
+//! Scheduled-prompt row shape on the wire, served by the dashboard's
+//! read-only schedule list (mirrors `hive-c0re`'s internal `scheduled_prompts::Schedule`).
 
 use chrono::{DateTime, Utc};
 use serde::{Deserialize, Serialize};
 
 /// Schedule row shape on the wire — mirror of
-/// `scheduled_prompts::Schedule` but in the public crate so the
-/// dashboard and agent surfaces can deserialize without depending
-/// on hive-c0re-internal types. Kept structurally identical to the
-/// in-process type; the conversion is field-by-field in
-/// `manager_server` / `dashboard`.
+/// `scheduled_prompts::Schedule` but in the public crate so a client
+/// can deserialize it without depending on hive-c0re-internal types.
+/// Kept structurally identical to the in-process type; the conversion
+/// is field-by-field in the dashboard.
 #[derive(Debug, Clone, Serialize, Deserialize)]
 pub struct WireSchedule {
     pub id: i64,
@@ -22,10 +21,7 @@ pub struct WireSchedule {
     pub source: WireScheduleSource,
     #[serde(default, skip_serializing_if = "Option::is_none")]
     pub cancelled_at_unix: Option<DateTime<Utc>>,
-    /// Set while the schedule is paused. Worker skips paused rows;
-    /// they keep their `next_fire_at_unix` so resuming at any time
-    /// fires at the next intended instant (no catch-up clamp needed
-    /// — a paused schedule simply slips its next fire).
+    /// Set if the row is paused.
     #[serde(default, skip_serializing_if = "Option::is_none")]
     pub paused_at_unix: Option<DateTime<Utc>>,
     #[serde(default, skip_serializing_if = "Option::is_none")]