refactor: 项目结构优化与FastAPI生命周期更新

重构项目目录结构，提高代码组织性和可维护性

将schemas目录重命名为domain，更好地表达领域模型概念
将services目录细分为service/chat、service/image等子目录
将api目录重命名为router，更符合FastAPI惯例
创建utils目录存放通用工具函数
更新FastAPI应用程序生命周期管理

替换已弃用的on_event方法为推荐的lifespan事件处理器
添加应用程序关闭时的日志记录
代码质量改进

抽取常量到constants.py，减少硬编码值
添加helpers.py提供通用工具函数
优化配置管理，使用环境变量和默认值
完善文档字符串，提高代码可读性

app/service/image/image_create_service.py

@@ -0,0 +1,155 @@
+import time
+import uuid
+
+from google import genai
+from google.genai import types
+import base64
+
+from app.config.config import settings
+from app.logger.logger import get_image_create_logger
+from app.utils.uploader import ImageUploaderFactory
+from app.domain.openai_models import ImageGenerationRequest
+from app.core.constants import VALID_IMAGE_RATIOS
+
+logger = get_image_create_logger()
+
+
+class ImageCreateService:
+    def __init__(self, aspect_ratio="1:1"):
+        self.image_model = settings.CREATE_IMAGE_MODEL
+        self.paid_key = settings.PAID_KEY
+        self.aspect_ratio = aspect_ratio
+
+    def parse_prompt_parameters(self, prompt: str) -> tuple:
+        """从prompt中解析参数
+        支持的格式:
+        - {n:数量} 例如: {n:2} 生成2张图片
+        - {ratio:比例} 例如: {ratio:16:9} 使用16:9比例
+        """
+        import re
+        
+        # 默认值
+        n = 1
+        aspect_ratio = self.aspect_ratio
+        
+        # 解析n参数
+        n_match = re.search(r'{n:(\d+)}', prompt)
+        if n_match:
+            n = int(n_match.group(1))
+            if n < 1 or n > 4:
+                raise ValueError(f"Invalid n value: {n}. Must be between 1 and 4.")
+            prompt = prompt.replace(n_match.group(0), '').strip()
+            
+        # 解析ratio参数    
+        ratio_match = re.search(r'{ratio:(\d+:\d+)}', prompt)
+        if ratio_match:
+            aspect_ratio = ratio_match.group(1)
+            if aspect_ratio not in VALID_IMAGE_RATIOS:
+                raise ValueError(
+                    f"Invalid ratio: {aspect_ratio}. Must be one of: {', '.join(VALID_IMAGE_RATIOS)}"
+                )
+            prompt = prompt.replace(ratio_match.group(0), '').strip()
+            
+        return prompt, n, aspect_ratio
+
+    def generate_images(self, request: ImageGenerationRequest):
+        client = genai.Client(api_key=self.paid_key)
+        
+        if request.size == "1024x1024":
+            self.aspect_ratio = "1:1"
+        elif request.size == "1792x1024":
+            self.aspect_ratio = "16:9"
+        elif request.size == "1027x1792":
+            self.aspect_ratio = "9:16"
+        else:
+            raise ValueError(
+                f"Invalid size: {request.size}. Supported sizes are 1024x1024, 1792x1024, and 1024x1792."
+            )
+
+        # 解析prompt中的参数
+        cleaned_prompt, prompt_n, prompt_ratio = self.parse_prompt_parameters(request.prompt)
+        request.prompt = cleaned_prompt
+        
+        # 如果prompt中指定了n，则覆盖请求中的n
+        if prompt_n > 1:
+            request.n = prompt_n
+            
+        # 如果prompt中指定了ratio，则覆盖默认的aspect_ratio
+        if prompt_ratio != self.aspect_ratio:
+            self.aspect_ratio = prompt_ratio
+
+        response = client.models.generate_images(
+            model=self.image_model,
+            prompt=request.prompt,
+            config=types.GenerateImagesConfig(
+                number_of_images=request.n,
+                output_mime_type="image/png",
+                aspect_ratio=self.aspect_ratio,
+                safety_filter_level="BLOCK_LOW_AND_ABOVE",
+                person_generation="ALLOW_ADULT",
+                # language="auto"
+            ),
+        )
+
+        if response.generated_images:
+            images_data = []
+            for index, generated_image in enumerate(response.generated_images):
+                image_data = generated_image.image.image_bytes
+                image_uploader = None
+                    
+                if request.response_format == "b64_json":
+                    base64_image = base64.b64encode(image_data).decode('utf-8')
+                    images_data.append({
+                        "b64_json": base64_image,
+                        "revised_prompt": request.prompt
+                    })
+                else:
+                    current_date = time.strftime("%Y/%m/%d")
+                    filename = f"{current_date}/{uuid.uuid4().hex[:8]}.png"
+                    
+                    if settings.UPLOAD_PROVIDER == "smms":
+                        image_uploader = ImageUploaderFactory.create(
+                            provider=settings.UPLOAD_PROVIDER,
+                            api_key=settings.SMMS_SECRET_TOKEN
+                        )
+                    elif settings.UPLOAD_PROVIDER == "picgo":
+                        image_uploader = ImageUploaderFactory.create(
+                            provider=settings.UPLOAD_PROVIDER,
+                            api_key=settings.PICGO_API_KEY
+                        )
+                    elif settings.UPLOAD_PROVIDER == "cloudflare_imgbed":
+                        image_uploader = ImageUploaderFactory.create(
+                            provider=settings.UPLOAD_PROVIDER,
+                            base_url=settings.CLOUDFLARE_IMGBED_URL,
+                            auth_code=settings.CLOUDFLARE_IMGBED_AUTH_CODE
+                        )
+                    else:
+                        raise ValueError(f"Unsupported upload provider: {settings.UPLOAD_PROVIDER}")
+                    
+                    upload_response = image_uploader.upload(image_data, filename)
+
+                    images_data.append({
+                        "url": f"{upload_response.data.url}",
+                        "revised_prompt": request.prompt
+                    })
+
+            response_data = {
+                "created": int(time.time()),  # Current timestamp
+                "data": images_data
+            }
+            return response_data
+        else:
+            raise Exception("I can't generate these images")
+
+    def generate_images_chat(self, request: ImageGenerationRequest) -> str:
+        response = self.generate_images(request)
+        image_datas = response["data"]
+        if image_datas:
+            markdown_images = []
+            for index, image_data in enumerate(image_datas):
+                if 'url' in image_data:
+                    markdown_images.append(f"![Generated Image {index+1}]({image_data['url']})")
+                else:
+                    # 如果是base64格式，创建data URL
+                    markdown_images.append(f"![Generated Image {index+1}](data:image/png;base64,{image_data['b64_json']})")
+            return "\n".join(markdown_images)