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/permissions.rs

@@ -162,9 +162,6 @@ pub enum ToolGroup {
     /// server-side gate: `cancel_loose_end`'s approval-cancel arm
     /// requires it (`socket_server::check_can_cancel_approval`).
     Approvals,
-    /// `request_schedule_prompt`, `fire_schedule_now`, `cancel_schedule`,
-    /// `edit_schedule`, `list_schedules` - *(privileged)*
-    Scheduling,
     /// Gates no tool today — `create_repo`, its only member, was removed
     /// with no replacement. Kept so existing `meta/capabilities.json`
     /// grants still parse; `tools()` returns `&[]`.
@@ -230,13 +227,6 @@ impl ToolGroup {
             Self::Messaging => &["send", "recv", "ack_until"],
             Self::Meta => &["get_agent_meta"],
             Self::Inbox => &["get_loose_ends", "cancel_loose_end", "remind"],
-            Self::Scheduling => &[
-                "request_schedule_prompt",
-                "fire_schedule_now",
-                "cancel_schedule",
-                "edit_schedule",
-                "list_schedules",
-            ],
             // All five empty, for different reasons — see each
             // variant's own doc comment above. `Execution` grants the
             // out-of-process `bash` MCP server
@@ -308,7 +298,6 @@ impl ToolGroup {
         Self::Inbox,
         Self::Lifecycle,
         Self::Approvals,
-        Self::Scheduling,
         Self::Execution,
     ];
 
@@ -321,7 +310,6 @@ impl ToolGroup {
         Self::Inbox,
         Self::Lifecycle,
         Self::Approvals,
-        Self::Scheduling,
         Self::Forge,
         Self::Execution,
         Self::WebTools,
@@ -340,9 +328,6 @@ impl ToolGroup {
             Self::Approvals => {
                 "no tools — grants cancel_loose_end's approval-cancel arm (privileged)"
             }
-            Self::Scheduling => {
-                "request_schedule_prompt and related — operator-visible scheduled prompts (privileged)"
-            }
             Self::Forge => "no tools — vestigial since create_repo was removed",
             Self::Execution => {
                 "run, status — run shell commands via mcp__bash__run / mcp__bash__status"