Add crypto signals pipeline + Polymarket arb scanner

- Signal parser for Telegram JSON exports
- Price fetcher using Binance US API
- Backtester with fee-aware simulation
- Polymarket 15-min arb scanner with orderbook checking
- Systemd timer every 2 min for arb alerts
- Paper trade tracking
- Investigation: polymarket-15min-arb.md

projects/crypto-signals/data/arb-scanner/scan_log.json

@@ -0,0 +1,20 @@
+[
+  {
+    "timestamp": "2026-02-09T20:27:10.137684+00:00",
+    "markets_scanned": 0,
+    "arbs_found": 0,
+    "opportunities": []
+  },
+  {
+    "timestamp": "2026-02-09T20:29:24.646570+00:00",
+    "markets_scanned": 0,
+    "arbs_found": 0,
+    "opportunities": []
+  },
+  {
+    "timestamp": "2026-02-09T20:30:04.391737+00:00",
+    "markets_scanned": 0,
+    "arbs_found": 0,
+    "opportunities": []
+  }
+]