Anomaly Search

Single-ticker anomaly check -- lets a user check ANY global ticker, separate from the batch watchlist scan above. Same AnomalyEngine math, same real volume/price data, just scoped to one symbol instead of the whole watchlist.

Unlike the batch endpoint above (which only lists tickers that actually have an anomaly, since it's a "what needs my attention" radar), this ALWAYS returns a result even when severity is NONE -- someone explicitly searching one ticker wants an honest "no anomaly detected" answer, not silence.

2026-07-31 fix ("顯示「攞唔到 AAPL 嘅市場數據...」" regardless of UI language): both error messages below used to be hardcoded Traditional Chinese literals, so an English/Japanese/etc-mode user searching an unrecognized or data-unavailable ticker still saw raw Cantonese. Now accepts lang (same param anomaly.html already sends everywhere else via I18N.currentLang) and looks the two messages up from services/i18n.py's per-language dict, defaulting to the original Chinese text for zh-HK/zh-TW/unset lang -- these are plain UI strings (not AI-generated prose), so a direct dict lookup is simpler and more reliable here than the ai_language_instruction() prompt-steering pattern used for LLM endpoints elsewhere.