feat: add HTTP/SOCKS5 proxy support for API endpoints

- Add proxy field to ProviderEndpoint database model with migration
- Add ProxyConfig Pydantic model for proxy URL validation
- Extend HTTP client pool with create_client_with_proxy method
- Integrate proxy configuration in chat_handler_base.py and cli_handler_base.py
- Update admin API endpoints to support proxy configuration CRUD
- Add proxy configuration UI in frontend EndpointFormDialog

Fixes #28

src/models/endpoint_models.py

@@ -8,6 +8,8 @@ from typing import Any, Dict, List, Optional
 
 from pydantic import BaseModel, ConfigDict, Field, field_validator
 
+from src.models.admin_requests import ProxyConfig
+
 # ========== ProviderEndpoint CRUD ==========
 
 
@@ -30,6 +32,9 @@ class ProviderEndpointCreate(BaseModel):
     # 额外配置
     config: Optional[Dict[str, Any]] = Field(default=None, description="额外配置（JSON）")
 
+    # 代理配置
+    proxy: Optional[ProxyConfig] = Field(default=None, description="代理配置")
+
     @field_validator("api_format")
     @classmethod
     def validate_api_format(cls, v: str) -> str:
@@ -64,6 +69,7 @@ class ProviderEndpointUpdate(BaseModel):
     rate_limit: Optional[int] = Field(default=None, ge=1, description="速率限制")
     is_active: Optional[bool] = Field(default=None, description="是否启用")
     config: Optional[Dict[str, Any]] = Field(default=None, description="额外配置")
+    proxy: Optional[ProxyConfig] = Field(default=None, description="代理配置")
 
     @field_validator("base_url")
     @classmethod
@@ -104,6 +110,9 @@ class ProviderEndpointResponse(BaseModel):
     # 额外配置
     config: Optional[Dict[str, Any]] = None
 
+    # 代理配置
+    proxy: Optional[Dict[str, Any]] = Field(default=None, description="代理配置")
+
     # 统计（从 Keys 聚合）
     total_keys: int = Field(default=0, description="总 Key 数量")
     active_keys: int = Field(default=0, description="活跃 Key 数量")