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/mod.rs

@@ -41,7 +41,7 @@ use crate::lifecycle;
         (name = "meta_inputs", description = "bulk flake-input update for the meta flake"),
         (name = "misc_api", description = "operator inbox, compose, spawn-request, hive stats"),
         (name = "permissions", description = "tool-group + capability assignment for agents"),
-        (name = "schedules", description = "scheduled-prompt + rebuild-queue CRUD"),
+        (name = "schedules", description = "read-only scheduled-prompt list + rebuild-queue cancel"),
         (name = "state_files", description = "proxied reads of allow-listed per-agent state files"),
         (name = "state_snapshot", description = "cold-load dashboard snapshot"),
         (name = "tombstones", description = "purge of retained state for destroyed agents"),
@@ -112,8 +112,7 @@ pub async fn serve(port: u16, coord: Arc<Coordinator>) -> Result<()> {
     // GET-vs-GET or POST-vs-POST pairs across different paths do. Each
     // call below is therefore scoped to exactly one path — two handlers
     // in the same call only when they genuinely share a path with
-    // different methods (`schedules::api_schedules`/`post_schedule_new`
-    // on `/api/schedules`) — chained via
+    // different methods — chained via
     // repeated `.routes(...)` calls instead of one giant `routes!(...)`
     // with everything in it.
     let (router, api) = OpenApiRouter::<AppState>::with_openapi(ApiDoc::openapi())
@@ -141,15 +140,7 @@ pub async fn serve(port: u16, coord: Arc<Coordinator>) -> Result<()> {
         .routes(routes!(permissions::post_permissions))
         .routes(routes!(permissions::get_stale_permissions))
         .routes(routes!(permissions::delete_agent_permissions))
-        .routes(routes!(
-            schedules::api_schedules,
-            schedules::post_schedule_new
-        ))
-        .routes(routes!(schedules::patch_schedule))
-        .routes(routes!(schedules::post_schedule_cancel))
-        .routes(routes!(schedules::post_schedule_pause))
-        .routes(routes!(schedules::post_schedule_resume))
-        .routes(routes!(schedules::post_schedule_fire_now))
+        .routes(routes!(schedules::api_schedules))
         .routes(routes!(schedules::post_rebuild_queue_cancel))
         .routes(routes!(approvals::post_approve))
         .routes(routes!(approvals::post_deny))
@@ -367,15 +358,7 @@ mod router_build_probe {
             .routes(routes!(permissions::post_permissions))
             .routes(routes!(permissions::get_stale_permissions))
             .routes(routes!(permissions::delete_agent_permissions))
-            .routes(routes!(
-                schedules::api_schedules,
-                schedules::post_schedule_new
-            ))
-            .routes(routes!(schedules::patch_schedule))
-            .routes(routes!(schedules::post_schedule_cancel))
-            .routes(routes!(schedules::post_schedule_pause))
-            .routes(routes!(schedules::post_schedule_resume))
-            .routes(routes!(schedules::post_schedule_fire_now))
+            .routes(routes!(schedules::api_schedules))
             .routes(routes!(schedules::post_rebuild_queue_cancel))
             .routes(routes!(approvals::post_approve))
             .routes(routes!(approvals::post_deny))