fix(ai): address issues from second code review

- Add STATUS_APPLIED and STATUS_DISMISSED constants to model
- Add markApplied() and markDismissed() methods
- Update event status after apply/dismiss actions (prevent duplicate ops)
- Validate related_task_id exists and user has permission
- Filter empty or overly long subtask names before creation

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via [Happy](https://happy.engineering)

Co-Authored-By: Claude <noreply@anthropic.com>
Co-Authored-By: Happy <yesreply@happy.engineering>

app/Models/ProjectTaskAiEvent.php

@@ -31,6 +31,8 @@ class ProjectTaskAiEvent extends AbstractModel
     const STATUS_COMPLETED = 'completed';
     const STATUS_FAILED = 'failed';
     const STATUS_SKIPPED = 'skipped';
+    const STATUS_APPLIED = 'applied';
+    const STATUS_DISMISSED = 'dismissed';
 
     const MAX_RETRY = 3;
 
@@ -129,4 +131,24 @@ class ProjectTaskAiEvent extends AbstractModel
         return $this->status === self::STATUS_FAILED
             && $this->retry_count < self::MAX_RETRY;
     }
+
+    /**
+     * 标记为已采纳
+     */
+    public function markApplied(): bool
+    {
+        return $this->update([
+            'status' => self::STATUS_APPLIED,
+        ]);
+    }
+
+    /**
+     * 标记为已忽略
+     */
+    public function markDismissed(): bool
+    {
+        return $this->update([
+            'status' => self::STATUS_DISMISSED,
+        ]);
+    }
 }