Use mo_task_migration() in mo_task_priority()

This change refactors the priority update process in mo_task_priority()
to include early-return checks and proper task migration handling.

- Early-return conditions:
  * Prevent modification of the idle task.
  * Disallow assigning TASK_PRIO_IDLE to non-idle tasks.
  The idle task is created by idle_task_init() during system startup and
  must retain its fixed priority.

- Task migration:
  If the priority-changed task resides in a ready queue (TASK_READY or
  TASK_RUNNING), sched_migrate_task() is called to move it to the queue
  corresponding to the new priority.

- Running task behavior:
  When the current running task changes its own priority, it yields the
  CPU so the scheduler can dispatch the next highest-priority task.

Author: vicLin8712

kernel/task.c

@@ -856,12 +856,22 @@ int32_t mo_task_priority(uint16_t id, uint16_t priority)
         return ERR_TASK_NOT_FOUND;
     }
 
+    bool is_current = (kcb->task_current->data == task);
+
+    /* Removed task from ready queue */
+    if (task->state == TASK_RUNNING || task->state == TASK_READY)
+        sched_migrate_task(task, priority);
+
     /* Update priority and level */
     task->prio = priority;
     task->prio_level = extract_priority_level(priority);
     task->time_slice = get_priority_timeslice(task->prio_level);
 
     CRITICAL_LEAVE();
+
+    if (is_current)
+        mo_task_yield();
+
     return ERR_OK;
 }