Backup current stock predictor strategies

feat: add SOX and TNX cross-asset features

feat: ML ensemble upgrade — LightGBM, cross-asset features, walk-forward embargo

fix: support TW ETF codes with letter suffix (00772B) and 6-digit codes (009816)

fix: replace unbounded caches with TTLCache to prevent memory leaks

feat: comprehensive optimization — 30 improvements across ML, perf, frontend, security, architecture

perf: indicator cache, quote TTL, twstock cache, yfinance timeout

feat: realtime quote (twstock + yfinance), today change %, 30s auto-refresh

fix: isolate yf.Ticker.info exception so _download_raw fallback runs for US tickers

fix: add 5s timeout to twstock import to prevent HF startup hang

fix+refactor: LINE webhook key bug, fetcher DRY, feature importance, async predictor service

feat: market tabs (台股/美股/基金), autocomplete search, favorites filter tabs

Add US stock and fund/ETF market support with ML prediction

fix: use twstock for Chinese stock names in get_stock_info

fix: Chinese stock name search using twstock local database

deploy: initial release