fix: emit SchedulesChanged from manager-server + approval paths

Agent-triggered schedule mutations (cancel_schedule, fire_schedule_now,
edit_schedule MCP tools) go through manager_server.rs, not the HTTP API
handlers. Approval-resolved SchedulePrompt inserts go through actions.rs.
Neither was emitting SchedulesChanged.

- manager_server.rs: add emit_schedules_snapshot() on Ok in
  handle_cancel_schedule, handle_fire_schedule_now, handle_edit_schedule
- actions.rs: emit_schedules_snapshot() after successful
  run_approval_schedule_prompt (covers request_schedule_prompt approval
  resolving)

Coverage is now complete: every path that writes a scheduled_prompts row
emits the SSE snapshot.

hive-c0re/src/actions.rs

@@ -116,7 +116,11 @@ pub async fn approve(coord: Arc<Coordinator>, id: i64) -> Result<()> {
             // at the scheduled time). Run inline + fire
             // `ApprovalResolved` so the approval row leaves Pending
             // immediately.
-            run_approval_schedule_prompt(&coord, approval).await
+            let result = run_approval_schedule_prompt(&coord, approval).await;
+            if result.is_ok() {
+                coord.emit_schedules_snapshot();
+            }
+            result
         }
     }
 }