feat(web): M8.6a 交易信号页（/signals）+ 导航与类型

- app/signals/page.tsx：因子+买卖排名阈值+时点+白名单 → BUY/WATCH/SELL 表格
  （类型 Pill 着色、得分/价格/触发理由）+ 最近信号记录回看
- app-shell 导航加入「交易信号」；lib/types.ts 增加 Signal* 类型与 universe.symbols
- 真实 MySQL 端到端：/api/signals 返回可解释信号（跌破 MA60 的 SELL 警示等）；
  /signals 页面 200；tsc --noEmit 通过

frontend/web/lib/types.ts

@@ -22,7 +22,11 @@ export interface FactorMeta {
 
 export interface ResearchSpec {
   type: "factor_test" | "backtest";
-  universe: { exclude_st?: boolean; min_listing_days?: number };
+  universe: {
+    exclude_st?: boolean;
+    min_listing_days?: number;
+    symbols?: string[];
+  };
   factors: { name: string; weight: number }[];
   selection: { top_n: number };
   rebalance: "weekly" | "monthly";
@@ -84,7 +88,11 @@ export interface SelectionCondition {
 }
 
 export interface SelectionQuery {
-  universe: { exclude_st?: boolean; min_listing_days?: number };
+  universe: {
+    exclude_st?: boolean;
+    min_listing_days?: number;
+    symbols?: string[];
+  };
   as_of?: string | null; // null/省略 = 最近交易日
   method: "score" | "condition";
   factors: { name: string; weight: number }[];
@@ -126,3 +134,46 @@ export interface SelectionRun {
   result: SelectionResult;
 }
 
+
+/* ---- 交易信号（v2 §15，与 domain/entities/signal.py 对应） ---- */
+
+export interface SignalRules {
+  buy_rank_threshold?: number;
+  buy_require_trend?: boolean;
+  buy_require_momentum?: boolean;
+  trend_ma?: number;
+  sell_rank_threshold?: number;
+  sell_on_trend_break?: boolean;
+  max_output_rank?: number;
+}
+
+export interface SignalEvent {
+  symbol: string;
+  signal_date: string;
+  signal_type: "BUY" | "WATCH" | "SELL";
+  score?: number | null;
+  price?: number | null;
+  trigger_reason: string[];
+}
+
+export interface SignalResult {
+  as_of_date: string;
+  rules: SignalRules;
+  statistics: { universe_size: number; buy: number; watch: number; sell: number };
+  events: SignalEvent[];
+  config_snapshot: Record<string, unknown>;
+}
+
+export interface SignalMeta {
+  id: string;
+  as_of: string;
+  buy: number;
+  watch: number;
+  sell: number;
+  created_at?: string | null;
+}
+
+export interface SignalRun {
+  signal_id: string;
+  result: SignalResult;
+}