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-c0re/src/dashboard_events.rs

@@ -48,24 +48,14 @@ pub enum DashboardEvent {
         #[serde(default, skip_serializing_if = "Vec::is_empty")]
         file_refs: Vec<String>,
     },
-    /// A new approval landed in the pending queue. Payload carries
-    /// enough to render the dashboard row without a `/api/state`
-    /// refetch.
-    ///
-    /// The approval's own kind (`"schedule_prompt"` / `"update_meta_inputs"`) lives
-    /// on `approval_kind` rather than `kind` because the latter is taken
-    /// by the serde tag identifying which `DashboardEvent` variant
-    /// this is.
-    ApprovalAdded {
-        seq: u64,
-        id: i64,
-        agent: String,
-        approval_kind: &'static str,
-        description: Option<String>,
-    },
     /// A pending approval transitioned to a terminal state
     /// (approved / denied / failed). Clients move the row out of the
     /// pending list and into history.
+    ///
+    /// The approval's own kind (`"update_meta_inputs"`) lives
+    /// on `approval_kind` rather than `kind` because the latter is taken
+    /// by the serde tag identifying which `DashboardEvent` variant
+    /// this is.
     ApprovalResolved {
         seq: u64,
         id: i64,
@@ -170,17 +160,6 @@ pub enum DashboardEvent {
     /// (transients, container state, approvals), and a poll loop would be
     /// slower for the same information.
     RebuildQueueChanged { seq: u64 },
-    /// Full snapshot of all scheduled prompts. Emitted after every
-    /// operator mutation (new / edit / cancel / fire-now) and after the
-    /// worker fires or rearms a row. Same snapshot-shape rationale as
-    /// `TombstonesChanged` / `MetaInputsChanged` — the list is small and the
-    /// client's
-    /// per-target `last_result` / `last_fired_at_unix` fields are most
-    /// naturally re-derived from the full list.
-    SchedulesChanged {
-        seq: u64,
-        schedules: Vec<hive_sh4re::schedule::WireSchedule>,
-    },
     /// Full snapshot of capability grants (per-agent `Vec<cap_name>`).
     /// Emitted from the rebuild-queue worker after a `PermChange`
     /// `Capabilities` entry commits the JSON file. Lets the P3RM1SS10NS
@@ -235,7 +214,6 @@ impl DashboardEvent {
         match self {
             DashboardEvent::Sent { .. } => "sent",
             DashboardEvent::Delivered { .. } => "delivered",
-            DashboardEvent::ApprovalAdded { .. } => "approval_added",
             DashboardEvent::ApprovalResolved { .. } => "approval_resolved",
             DashboardEvent::TransientSet { .. } => "transient_set",
             DashboardEvent::TransientCleared { .. } => "transient_cleared",
@@ -245,7 +223,6 @@ impl DashboardEvent {
             DashboardEvent::MetaInputsChanged { .. } => "meta_inputs_changed",
             DashboardEvent::MetaUpdateRunning { .. } => "meta_update_running",
             DashboardEvent::RebuildQueueChanged { .. } => "rebuild_queue_changed",
-            DashboardEvent::SchedulesChanged { .. } => "schedules_changed",
             DashboardEvent::CapabilitiesChanged { .. } => "capabilities_changed",
             DashboardEvent::ToolGroupsChanged { .. } => "tool_groups_changed",
         }
@@ -294,18 +271,11 @@ mod tests {
                 in_reply_to: None,
                 file_refs: Vec::new(),
             },
-            DashboardEvent::ApprovalAdded {
-                seq: 1,
-                id: 1,
-                agent: "x".into(),
-                approval_kind: "schedule_prompt",
-                description: None,
-            },
             DashboardEvent::ApprovalResolved {
                 seq: 1,
                 id: 1,
                 agent: "x".into(),
-                approval_kind: "schedule_prompt",
+                approval_kind: "update_meta_inputs",
                 status: "approved",
                 resolved_at: hive_sh4re::wire_time::from_secs(0),
                 note: None,
@@ -339,10 +309,6 @@ mod tests {
                 running: false,
             },
             DashboardEvent::RebuildQueueChanged { seq: 1 },
-            DashboardEvent::SchedulesChanged {
-                seq: 1,
-                schedules: Vec::new(),
-            },
             DashboardEvent::CapabilitiesChanged {
                 seq: 1,
                 caps: Vec::new(),