feat: swagger 친구요청 상태 업데이트

[DongilMin]

/**
 * @swagger
 * /api/friends/search:
 *   get:
 *     summary: 닉네임으로 친구 검색
 *     tags: [Friends]
 *     security:
 *       - bearerAuth: []
 *     parameters:
 *       - in: query
 *         name: nickname
 *         required: true
 *         schema:
 *           type: string
 *         description: 검색할 닉네임 (완전일치)
 *     responses:
 *       200:
 *         description: 사용자 검색 성공
 *         content:
 *           application/json:
 *             schema:
 *               type: object
 *               properties:
 *                 success:
 *                   type: boolean
 *                   example: true
 *                 data:
 *                   type: array
 *                   items:
 *                     type: object
 *                     properties:
 *                       userId:
 *                         type: number
 *                         example: 789
 *                       nickname:
 *                         type: string
 *                         example: 검색된닉네임
 *                       profileImage:
 *                         type: string
 *                         nullable: true
 *                         example: 프로필이미지URL
 *                       popularity:
 *                         type: number
 *                         example: 80
 *                       requestStatus:   
 *                         type: string
 *                         enum: ['none', 'pending', 'accepted', 'rejected']
 *                         description: 친구 요청 상태
 *                         example: pending
 */