feat(ai): 升级AI生图模型及多视角一致性支持

- 将默认AI生图模型升级为flux-dev及seedream-5.0版本
- SiliconFlow模型由FLUX.1-dev切换为Kolors，优化调用参数和返回值
- 火山引擎Seedream升级至5.0 lite版本，支持多视角参考图传入
- 设计图片字段由字符串改为Text扩展URL长度限制
- 设计图下载支持远程URL重定向和本地文件兼容
- 生成AI图片时多视角保持风格一致，SiliconFlow复用seed，Seedream传参考图
- 后台配置界面更改模型名称及价格显示，新增API Key状态检测
- 前端照片下载从链接改为按钮，远程文件新窗口打开
- 设计相关接口支持较长请求超时，下载走API路径无/api前缀
- 前端页面兼容驼峰与下划线格式URL参数识别
- 用户中心设计图下载支持本地文件Token授权下载
- 初始化数据库新增完整表结构与约束，适配新版设计业务逻辑

backend/app/services/ai_generator.py

@@ -1,12 +1,12 @@
 """
 AI 生图服务
-支持双模型：SiliconFlow FLUX.1 [dev] 和 火山引擎 Seedream 4.5
+支持双模型：SiliconFlow Kolors 和 火山引擎 Seedream 5.0 lite
 """
 import os
 import uuid
 import logging
 import httpx
-from typing import Optional
+from typing import Optional, Tuple
 
 from ..config import settings
 from .config_service import get_ai_config
@@ -19,12 +19,15 @@ REQUEST_TIMEOUT = 90
 MAX_RETRIES = 3
 
 
-async def _call_siliconflow(prompt: str, size: int = 1024, ai_config: dict = None) -> str:
+async def _call_siliconflow(prompt: str, size: int = 1024, ai_config: dict = None, seed: Optional[int] = None) -> Tuple[str, Optional[int]]:
     """
-    调用 SiliconFlow FLUX.1 [dev] 生图 API
+    调用 SiliconFlow 生图 API（Kolors 模型）
+    
+    Args:
+        seed: 随机种子，传入相同 seed 可保持多视角图片风格一致
     
     Returns:
-        远程图片 URL
+        (远程图片 URL, 使用的 seed)
     """
     cfg = ai_config or get_ai_config()
     url = f"{cfg['SILICONFLOW_BASE_URL']}/images/generations"
@@ -33,30 +36,38 @@ async def _call_siliconflow(prompt: str, size: int = 1024, ai_config: dict = Non
         "Content-Type": "application/json",
     }
     payload = {
-        "model": "black-forest-labs/FLUX.1-dev",
+        "model": "Kwai-Kolors/Kolors",
         "prompt": prompt,
         "image_size": f"{size}x{size}",
+        "batch_size": 1,
         "num_inference_steps": 20,
+        "guidance_scale": 7.5,
     }
+    if seed is not None:
+        payload["seed"] = seed
 
     async with httpx.AsyncClient(timeout=REQUEST_TIMEOUT) as client:
         resp = await client.post(url, json=payload, headers=headers)
         resp.raise_for_status()
         data = resp.json()
 
-    # SiliconFlow 响应格式: {"images": [{"url": "https://..."}]}
+    # SiliconFlow 响应格式: {"images": [{"url": "https://..."}], "seed": 12345}
     images = data.get("images", [])
     if not images:
         raise ValueError("SiliconFlow 返回空图片列表")
-    return images[0]["url"]
+    returned_seed = data.get("seed")
+    return images[0]["url"], returned_seed
 
 
-async def _call_seedream(prompt: str, size: int = 1024, ai_config: dict = None) -> str:
+async def _call_seedream(prompt: str, size: int = 1024, ai_config: dict = None, seed: Optional[int] = None, ref_image_url: Optional[str] = None) -> Tuple[str, Optional[int]]:
     """
-    调用火山引擎 Seedream 4.5 生图 API
+    调用火山引擎 Seedream 5.0 lite 生图 API
+    
+    Args:
+        ref_image_url: 参考图 URL，用于多视角一致性（将第一张图作为参考传入后续视角）
     
     Returns:
-        远程图片 URL
+        (远程图片 URL, seed)
     """
     cfg = ai_config or get_ai_config()
     url = f"{cfg['VOLCENGINE_BASE_URL']}/images/generations"
@@ -65,37 +76,42 @@ async def _call_seedream(prompt: str, size: int = 1024, ai_config: dict = None)
         "Content-Type": "application/json",
     }
     payload = {
-        "model": "doubao-seedream-4.5-t2i-250528",
+        "model": "doubao-seedream-5-0-260128",
         "prompt": prompt,
-        "size": f"{size}x{size}",
+        "size": "2K",
         "response_format": "url",
+        "watermark": False,
     }
+    # 传入参考图保持多视角一致性（API 要求数组格式）
+    if ref_image_url:
+        payload["image"] = [ref_image_url]
 
     async with httpx.AsyncClient(timeout=REQUEST_TIMEOUT) as client:
         resp = await client.post(url, json=payload, headers=headers)
-        resp.raise_for_status()
+        if resp.status_code != 200:
+            logger.error(f"Seedream API 错误: status={resp.status_code}, body={resp.text[:500]}")
+            resp.raise_for_status()
         data = resp.json()
 
     # Seedream 响应格式: {"data": [{"url": "https://..."}]}
     items = data.get("data", [])
     if not items:
         raise ValueError("Seedream 返回空图片列表")
-    return items[0]["url"]
+    return items[0]["url"], seed
 
 
-async def generate_image(prompt: str, model: Optional[str] = None) -> str:
+async def generate_image(prompt: str, model: Optional[str] = None, seed: Optional[int] = None, ref_image_url: Optional[str] = None) -> Tuple[str, Optional[int]]:
     """
     统一生图接口，带重试机制
     
     Args:
-        prompt: 英文提示词
-        model: 模型名称 (flux-dev / seedream-4.5)，为空则使用配置默认值
+        prompt: 提示词
+        model: 模型名称 (flux-dev / seedream-5.0)
+        seed: 随机种子（SiliconFlow Kolors 支持）
+        ref_image_url: 参考图 URL（Seedream 5.0 支持，用于多视角一致性）
         
     Returns:
-        远程图片 URL
-        
-    Raises:
-        Exception: 所有重试失败后抛出
+        (远程图片 URL, 使用的 seed)
     """
     ai_config = get_ai_config()
     model = model or ai_config.get("AI_IMAGE_MODEL", "flux-dev")
@@ -104,12 +120,12 @@ async def generate_image(prompt: str, model: Optional[str] = None) -> str:
     last_error: Optional[Exception] = None
     for attempt in range(1, MAX_RETRIES + 1):
         try:
-            if model == "seedream-4.5":
-                image_url = await _call_seedream(prompt, size, ai_config)
+            if model in ("seedream-5.0", "seedream-4.5"):
+                image_url, returned_seed = await _call_seedream(prompt, size, ai_config, seed, ref_image_url)
             else:
-                image_url = await _call_siliconflow(prompt, size, ai_config)
-            logger.info(f"AI 生图成功 (model={model}, attempt={attempt})")
-            return image_url
+                image_url, returned_seed = await _call_siliconflow(prompt, size, ai_config, seed)
+            logger.info(f"AI 生图成功 (model={model}, seed={returned_seed}, attempt={attempt})")
+            return image_url, returned_seed
         except Exception as e:
             last_error = e
             logger.warning(f"AI 生图失败 (model={model}, attempt={attempt}/{MAX_RETRIES}): {e}")