[BugFix] Fix noisy output without setting a seed in Qwen Image

[natureofnature]

PLEASE FILL IN THE PR DESCRIPTION HERE ENSURING ALL CHECKLIST ITEMS (AT THE BOTTOM) HAVE BEEN CONSIDERED.

Purpose

Fix #959
Reason: Without specifying a random seed, the random noise in multiprocessing/distributed environments may not be correctly synchronized.
Methods: add default random seed to api server

Test Plan

Test Result

from openai import OpenAI

import base64
import os
from datetime import datetime
client = OpenAI(base_url="http://localhost:40021/v1", api_key="none")

response = client.images.generate(
    model="/home/natureofnature/models/Qwen-Image-2512/",
    prompt="a horse jumping over a fence nearby a babbling brook",
    n=1,
    size="1024x1024",
    response_format="b64_json",
)

for idx, image in enumerate(response.data):
    image_data = base64.b64decode(image.b64_json)
    
    timestamp = datetime.now().strftime("%Y%m%d_%H%M%S")
    filename = f"generated_image_{timestamp}_{idx}.png"
    
    with open(filename, "wb") as f:
        f.write(image_data)
    
    print(f"Image saved to: {filename}")

---

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• The purpose of the PR, such as "Fix some issue (link existing issues this PR will resolve)".
• The test plan, such as providing test command.
• The test results, such as pasting the results comparison before and after, or e2e results
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[david6666666]

LGTM