Expand formatSymbolForTradingView to map 40+ Finnhub exchange suffixes
to their TradingView prefix equivalents. Previously only .SS, .SZ, and
.HK were handled, causing international symbols like 2330.TW to fail
on the stock details page.
Add comprehensive test suite for utility functions including
formatSymbolForTradingView, formatMarketCapValue, formatChangePercent,
getChangeColorClass, and calculateNewsDistribution.
Closes#24
02a3a68267