feat(download): 添加快手下载器并优化下载配置功能

- 新增快手下载器，支持快手视频下载
- 添加下载配置页面，可设置各平台Cookies
- 优化后端接口，增加获取和更新Cookies的功能
- 前端新增Downloader组件和相关表单组件
- 更新路由配置，增加下载配置相关路由

backend/app/validators/video_url_validator.py

@@ -1,24 +1,30 @@
-from pydantic import AnyUrl, validator, BaseModel
+from pydantic import AnyUrl, validator, BaseModel, field_validator
 import re
 
 SUPPORTED_PLATFORMS = {
     "bilibili": r"(https?://)?(www\.)?bilibili\.com/video/[a-zA-Z0-9]+",
     "youtube": r"(https?://)?(www\.)?(youtube\.com/watch\?v=|youtu\.be/)[\w\-]+",
-    "douyin": r"'http[s]?://(?:[a-zA-Z]|[0-9]|[$-_@.&+]|[!*\(\),]|(?:%[0-9a-fA-F][0-9a-fA-F])"
-
+    "douyin": "douyin",
+    "kuaishou": "kuaishou"
 }
 
 
-
 def is_supported_video_url(url: str) -> bool:
-    return any(re.match(pattern, url) for pattern in SUPPORTED_PLATFORMS.values())
+    for name, pattern in SUPPORTED_PLATFORMS.items():
+        if pattern in ["douyin", "kuaishou"]:
+            if pattern in url:
+                return True
+        else:
+            if re.match(pattern, url):
+                return True
+    return False
 
 
 class VideoRequest(BaseModel):
     url: AnyUrl
     platform: str
 
-    @validator("url")
+    @field_validator("url")
     def validate_video_url(cls, v):
         if not is_supported_video_url(str(v)):
             raise ValueError("暂不支持该视频平台或链接格式无效")