重构: 迁移后端代码到 app 目录，前端移动到 WebUI，添加完整测试套件

主要变更:
- 后端代码从根目录迁移到 app/ 目录
- 前端代码从 frontend/ 重命名为 WebUI/
- 更新所有导入路径以适配新结构
- 提取公共 API 响应函数到 app/api/common.py
- 精简验证器服务代码
- 更新启动脚本和文档

测试:
- 新增完整测试套件 (tests/)
- 单元测试: 模型、仓库层
- 集成测试: 覆盖所有 22+ API 端点
- E2E 测试: 4个完整工作流场景
- 添加 pytest 配置和测试运行脚本

app/models/__init__.py

@@ -0,0 +1,30 @@
+"""数据模型包"""
+from .domain import ProxyRaw, Proxy, PluginInfo
+from .schemas import (
+    ProxyCreate,
+    ProxyResponse,
+    PluginResponse,
+    SettingsSchema,
+    CrawlResult,
+    ProxyListRequest,
+    ProxyDeleteItem,
+    BatchDeleteRequest,
+    PluginToggleRequest,
+    ExportRequest,
+)
+
+__all__ = [
+    "ProxyRaw",
+    "Proxy",
+    "PluginInfo",
+    "ProxyCreate",
+    "ProxyResponse",
+    "PluginResponse",
+    "SettingsSchema",
+    "CrawlResult",
+    "ProxyListRequest",
+    "ProxyDeleteItem",
+    "BatchDeleteRequest",
+    "PluginToggleRequest",
+    "ExportRequest",
+]

app/models/domain.py

@@ -0,0 +1,42 @@
+"""领域模型 - 纯数据结构，不依赖任何框架"""
+from dataclasses import dataclass, field
+from datetime import datetime
+from typing import Optional
+
+
+@dataclass
+class ProxyRaw:
+    """爬虫爬取的原始代理数据"""
+    ip: str
+    port: int
+    protocol: str = "http"
+
+    def __post_init__(self):
+        self.protocol = self.protocol.lower().strip()
+        if self.protocol not in ("http", "https", "socks4", "socks5"):
+            self.protocol = "http"
+
+
+@dataclass
+class Proxy:
+    """数据库中的代理实体"""
+    ip: str
+    port: int
+    protocol: str
+    score: int
+    response_time_ms: Optional[float] = None
+    last_check: Optional[datetime] = None
+    created_at: Optional[datetime] = None
+
+
+@dataclass
+class PluginInfo:
+    """插件元数据"""
+    id: str
+    name: str
+    display_name: str
+    description: str
+    enabled: bool
+    last_run: Optional[datetime] = None
+    success_count: int = 0
+    failure_count: int = 0

app/models/schemas.py

@@ -0,0 +1,105 @@
+"""Pydantic 模型 - 用于 API 请求/响应校验"""
+from pydantic import BaseModel, Field, field_validator
+from typing import Optional, List
+
+
+class ProxyCreate(BaseModel):
+    ip: str
+    port: int = Field(ge=1, le=65535)
+    protocol: str = "http"
+    score: int = Field(default=10, ge=0, le=100)
+
+    @field_validator("protocol")
+    @classmethod
+    def validate_protocol(cls, v: str):
+        v = v.lower().strip()
+        if v not in ("http", "https", "socks4", "socks5"):
+            raise ValueError("protocol must be http, https, socks4 or socks5")
+        return v
+
+
+class ProxyResponse(BaseModel):
+    ip: str
+    port: int
+    protocol: str
+    score: int
+    last_check: Optional[str] = None
+
+
+class PluginResponse(BaseModel):
+    id: str
+    name: str
+    display_name: str
+    description: str
+    enabled: bool
+    last_run: Optional[str] = None
+    success_count: int = 0
+    failure_count: int = 0
+
+
+class SettingsSchema(BaseModel):
+    crawl_timeout: int = Field(default=30, ge=5, le=120)
+    validation_timeout: int = Field(default=10, ge=3, le=60)
+    max_retries: int = Field(default=3, ge=0, le=10)
+    default_concurrency: int = Field(default=50, ge=10, le=200)
+    min_proxy_score: int = Field(default=0, ge=0, le=100)
+    proxy_expiry_days: int = Field(default=7, ge=1, le=30)
+    auto_validate: bool = True
+    validate_interval_minutes: int = Field(default=30, ge=5, le=1440)
+
+
+class CrawlResult(BaseModel):
+    plugin_id: str
+    proxy_count: int
+    valid_count: int
+    invalid_count: int = 0
+
+
+class ProxyListRequest(BaseModel):
+    page: int = Field(default=1, ge=1)
+    page_size: int = Field(default=20, ge=1, le=100)
+    protocol: Optional[str] = None
+    min_score: int = Field(default=0, ge=0)
+    max_score: Optional[int] = Field(default=None, ge=0)
+    sort_by: str = "last_check"
+    sort_order: str = "DESC"
+
+    @field_validator("protocol")
+    @classmethod
+    def validate_protocol(cls, v):
+        if v is not None and v.lower() not in ("http", "https", "socks4", "socks5"):
+            raise ValueError("协议类型必须是 http, https, socks4 或 socks5")
+        return v.lower() if v else v
+
+    @field_validator("sort_by")
+    @classmethod
+    def validate_sort_by(cls, v):
+        if v not in ("ip", "port", "protocol", "score", "last_check"):
+            raise ValueError("排序字段必须是 ip, port, protocol, score 或 last_check")
+        return v
+
+    @field_validator("sort_order")
+    @classmethod
+    def validate_sort_order(cls, v):
+        if v.upper() not in ("ASC", "DESC"):
+            raise ValueError("排序方式必须是 ASC 或 DESC")
+        return v.upper()
+
+
+class ProxyDeleteItem(BaseModel):
+    ip: str
+    port: int = Field(ge=1, le=65535)
+
+
+class BatchDeleteRequest(BaseModel):
+    proxies: List[ProxyDeleteItem] = Field(max_length=1000)
+
+
+class PluginToggleRequest(BaseModel):
+    enabled: bool
+
+
+class ExportRequest(BaseModel):
+    format: str = Field(pattern=r"^(csv|txt|json)$")
+    protocol: Optional[str] = None
+    limit: int = Field(default=10000, ge=1, le=100000)