refactor: migrate API keys to config, extend Kline intervals, add DB extensions

Security:
- Move hardcoded Binance API key/secret from rest.ts to env.yaml (exchange config segment)
- Add ExchangeConfig validation in config/validators.ts
- Export typed exchange config from config/index.ts
- Update AGENTS/07-caveats.md to reflect the new policy

Kline intervals (add 3m / 2h / 6h / 8h / 1mon):
- TypeScript: update KlineInterval type, KLINE_INTERVAL_MS mapping, build_aggregates_sql refresh chain
- Python: sync KlineInterval Literal type, INTERVAL_TO_TABLE and INTERVAL_MS mappings, db_test table list
- SQL: add 5 continuous aggregate materialized views (klines_3m/2h/6h/8h/1mon) with indexes
- SQL: extend default kline_intervals in trading_pairs table
- SQL: add cross-sectional query indexes for klines_1d and klines_1w

DB:
- Enable pg_prewarm extension (backtest warmup)
- Enable pg_stat_statements extension (slow query monitoring)

Other:
- data/run/exchange.ts: graceful pgsql shutdown after backfill completes
- Config path: load from data/env.yaml (symlink) instead of project root

data/exchanges/rest.ts

@@ -1,19 +1,25 @@
 import { MainClient, type Kline as BinanceRestKline } from "binance";
 
 import { logger } from "../utils/logger";
+import { exchange } from "../config";
 import { BaseRestClient } from './base_rest';
 import type { KlineInterval, Kline, MarketInfo } from '../types';
 
 /** K 线周期 → 毫秒数映射（用于时间桶计算） */
 export const KLINE_INTERVAL_MS: Record<KlineInterval, number> = {
     "1m": 60_000,
+    "3m": 180_000,
     "5m": 300_000,
     "15m": 900_000,
     "30m": 1_800_000,
     "1h": 3_600_000,
+    "2h": 7_200_000,
     "4h": 14_400_000,
+    "6h": 21_600_000,
+    "8h": 28_800_000,
     "1d": 86_400_000,
     "1w": 604_800_000,
+    "1mon": 2_592_000_000,
 };
 
 // ============================================================
@@ -102,8 +108,8 @@ async function fetchBinanceKlines(
     limit = 500,
 ): Promise<Kline[]> {
     const client = new MainClient({
-        api_key: 'ONSJKIGRpDYLn6FdV17aAKfjclZ4I2LzamflhuMpsoRQA427lLKeyJlGtg2RZ7DH',
-        api_secret: '5Mfv4TgvDlRzCHbtl2nJL4mVHUvMm8pyjKiRjMoosBMxrhlqMw6CuQbg2qbS2Npd',
+        api_key: exchange.binance.apiKey,
+        api_secret: exchange.binance.apiSecret,
     }, {
         timeout: 3000,
     });