Rewrite price lookup from WebSocket to REST API

Replace unreliable WebSocket connections with on-demand REST API calls
for spot and futures prices. Add cached trading pair list (refreshed
hourly) for symbol validation, and /refresh command for manual updates.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

internal/services/tele/commands/market.go

@@ -2,6 +2,7 @@ package commands
 
 import (
 	"gopkg.in/telebot.v3"
+	"me.thuanle/bbot/internal/data"
 	"me.thuanle/bbot/internal/services/controllers"
 	"me.thuanle/bbot/internal/services/tele/chat"
 	"me.thuanle/bbot/internal/services/tele/view"
@@ -16,3 +17,8 @@ func OnGetTopFundingFee(context telebot.Context) error {
 	fee, float64s, cds := controllers.GetTopFundingFee()
 	return chat.ReplyMessagePre(context, view.RenderOnGetTopFundingFeeMessage(fee, float64s, cds))
 }
+
+func OnRefreshPairCache(context telebot.Context) error {
+	data.Market.RefreshTradingPairCache()
+	return chat.ReplyMessage(context, "Trading pair cache refreshed")
+}