The TCBS `apipubaws.tcbs.com.vn` host returns HTTP 404/500 for every
request, so every ticker resolved as "Unknown stock ticker" and /trade_buy
was unusable. Switch price + symbol resolution to the KBS public endpoint
that vnstock currently defaults to (`kbbuddywts.kbsec.com.vn/iis-server/
investment/stocks/{TICKER}/data_day`). KBS needs no auth, returns JSON,
and is Worker-compatible.
- `prices.fetchStockPrice` now queries KBS with a 14-day lookback window
(covers weekends/holidays) and drops the TCBS-specific ×1000 scaling;
KBS returns real VND.
- `symbols.resolveSymbol` delegates to `fetchStockPrice` for existence
checks — empty `data_day` means unknown ticker.
- Update test fetch stubs to match the `kbsec` host and KBS response
shape (`{ symbol, data_day: [{ c }] }`).
Replace hardcoded 9-symbol registry with dynamic TCBS-based resolution.
Any VN stock ticker is now resolved on first use and cached in KV
permanently. Portfolio flattened from 4 category maps to single assets
map with automatic migration of old format. Crypto, gold, and currency
exchange disabled with "coming soon" message.
Paper trading system with 5 commands (trade_topup, trade_buy,
trade_sell, trade_convert, trade_stats). Supports VN stocks via TCBS,
crypto via CoinGecko, forex via ER-API, and gold via PAX Gold proxy.
Per-user portfolio stored in KV with 60s price caching. 54 new tests.
tiennm99