feat(core): 完成 Phase 2 核心功能开发

- 实现查询API (query.py): 支持star_id/unique_id/nickname三种查询方式
- 实现计算模块 (calculator.py): CPM/自然搜索UV/搜索成本计算
- 实现品牌API集成 (brand_api.py): 批量并发调用，10并发限制
- 实现导出服务 (export_service.py): Excel/CSV导出
- 前端组件: QueryForm/ResultTable/ExportButton
- 主页面集成: 支持6种页面状态
- 测试: 44个测试全部通过，覆盖率88%

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

backend/app/schemas/query.py

@@ -0,0 +1,67 @@
+from pydantic import BaseModel, ConfigDict, Field
+from typing import List, Literal, Optional
+from datetime import datetime
+
+
+class QueryRequest(BaseModel):
+    """查询请求模型."""
+
+    type: Literal["star_id", "unique_id", "nickname"] = Field(
+        ..., description="查询类型: star_id, unique_id, nickname"
+    )
+    values: List[str] = Field(
+        ..., description="查询值列表 (批量ID 或单个昵称)", min_length=1
+    )
+
+
+class VideoData(BaseModel):
+    """视频数据模型."""
+
+    # 基础信息
+    item_id: str
+    title: Optional[str] = None
+    viral_type: Optional[str] = None
+    video_url: Optional[str] = None
+    star_id: str
+    star_unique_id: str
+    star_nickname: str
+    publish_time: Optional[datetime] = None
+
+    # 曝光指标
+    natural_play_cnt: int = 0
+    heated_play_cnt: int = 0
+    total_play_cnt: int = 0
+
+    # 互动指标
+    total_interact: int = 0
+    like_cnt: int = 0
+    share_cnt: int = 0
+    comment_cnt: int = 0
+
+    # 效果指标
+    new_a3_rate: Optional[float] = None
+    after_view_search_uv: int = 0
+    return_search_cnt: int = 0
+
+    # 商业信息
+    industry_id: Optional[str] = None
+    industry_name: Optional[str] = None
+    brand_id: Optional[str] = None
+    brand_name: Optional[str] = None  # 从品牌 API 获取
+    estimated_video_cost: float = 0
+
+    # 计算字段
+    estimated_natural_cpm: Optional[float] = None
+    estimated_natural_search_uv: Optional[float] = None
+    estimated_natural_search_cost: Optional[float] = None
+
+    model_config = ConfigDict(from_attributes=True)
+
+
+class QueryResponse(BaseModel):
+    """查询响应模型."""
+
+    success: bool = True
+    data: List[VideoData] = []
+    total: int = 0
+    error: Optional[str] = None