refactor: 删除板块资金流向，题材板块功能更全

- 删除前端 /sectors 页面、首页入口按钮、stock-api 板块类型与 fetchSectors
- 删除后端 /api/sectors 路由，main.py 移除注册
- eastmoney.py 移除板块数据段(_fetch_push2/_fetch_akshare/UT令牌管理)，
  清理重复 import 与无用 datetime 子导入
- mootdx.py 移除板块降级方案(fetch_sector_list)
- routeTree.gen.ts 由 build 自动重新生成，移除 sectors 路由

题材热点/热点穿透/核心股已覆盖板块能力，功能更全，板块资金流向不再需要

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

src/lib/stock-api.ts

@@ -430,50 +430,3 @@ export async function fetchFinancialData(code: string, years: number = 5): Promi
   }
 }
 
-// ---- 板块数据 ----
-
-export interface SectorItem {
-  code: string;
-  name: string;
-  level: number | null;
-  changePercent: number | null;
-  changeAmount: number | null;
-  mainNetInflow: number;
-  mainNetInflowPercent: number | null;
-  superLargeInflow: number | null;
-  superLargeInflowPercent: number | null;
-  largeInflow: number | null;
-  largeInflowPercent: number | null;
-  mediumInflow: number | null;
-  mediumInflowPercent: number | null;
-  smallInflow: number | null;
-  smallInflowPercent: number | null;
-  turnover: number;
-}
-
-export type SectorType = "industry" | "concept";
-
-export interface SectorResponse {
-  data: SectorItem[];
-  count: number;
-  type: SectorType;
-}
-
-/**
- * 获取东方财富板块列表（按主力净流入排序）
- * @param type industry=行业板块, concept=概念板块
- */
-export async function fetchSectors(type: SectorType, signal?: AbortSignal): Promise<SectorItem[]> {
-  const baseUrl = getApiBaseUrl();
-  const url = `${baseUrl}/api/sectors?type=${type}`;
-
-  try {
-    const resp = await fetch(url, { method: "GET", signal, cache: "no-store" });
-    if (!resp.ok) return [];
-    const result: SectorResponse = await resp.json();
-    return result.data || [];
-  } catch (err) {
-    console.error("[stock-api] 获取板块数据失败:", err);
-    return [];
-  }
-}