Add Insiders tab with diverging bar chart and transaction table

- Backend: get_insider_transactions() in data_service (yfinance, 1hr TTL)
- Backend: InsidersResponse schema + GET /api/tickers/{symbol}/insiders
- Frontend: InsidersPage with 4-KPI strip, SVG diverging bar chart (),
  psm-insider transaction rows, pill filter toggles, shimmer skeleton,
  empty/error states
- Enable Insiders nav item (remove disabled flag)

1 files changed, 28 insertions, 0 deletions

diff --git a/frontend/types/api.ts b/frontend/types/api.ts
index c8fc26b..c65d3d2 100644
--- a/frontend/types/api.ts
+++ b/frontend/types/api.ts
@@ -164,6 +164,34 @@ export type RatioPoint = {
   vs_sector: number | null;
 };
 
+export type InsiderTransaction = {
+  date: string | null;
+  insider: string;
+  position: string;
+  direction: "buy" | "sell" | "other";
+  shares: number | null;
+  value: number | null;
+};
+
+export type InsiderMonthPoint = {
+  month: string;
+  buy: number;
+  sell: number;
+};
+
+export type InsiderSummary = {
+  buy_count: number;
+  sell_count: number;
+  buy_value: number;
+  sell_value: number;
+};
+
+export type InsidersResponse = {
+  summary: InsiderSummary;
+  monthly_chart: InsiderMonthPoint[];
+  transactions: InsiderTransaction[];
+};
+
 export type RatiosResponse = {
   pe_ttm: RatioPoint;
   ev_ebitda: RatioPoint;