feat: add real-time price fetching and fix data delays

- Add get_ticker() method for real-time quotes across all markets

- Add get_realtime_price() service with ticker/kline fallback chain

- Fix yfinance end date issue for US stocks and futures

- Fix forex timezone parsing for Tiingo UTC timestamps

- Add retry mechanism with exponential backoff for Tiingo API

- Add API rate limiting for portfolio (3 concurrent, 0.3s interval)

- Add force refresh option to bypass price cache on manual refresh

quantdinger_vue/src/api/portfolio.js

@@ -5,10 +5,11 @@ import request from '@/utils/request'
 
 // ==================== Positions ====================
 
-export function getPositions () {
+export function getPositions (params = {}) {
   return request({
     url: '/api/portfolio/positions',
-    method: 'get'
+    method: 'get',
+    params
   })
 }
 
@@ -35,10 +36,11 @@ export function deletePosition (id) {
   })
 }
 
-export function getPortfolioSummary () {
+export function getPortfolioSummary (params = {}) {
   return request({
     url: '/api/portfolio/summary',
-    method: 'get'
+    method: 'get',
+    params
   })
 }