fix: full arb table + net profit columns in price view

- ArbTable: removed slice(0,10) cap, shows all 42 opps (21x2)
- PriceTable: added net_bg_to_hl and net_hl_to_bg columns
- Backend SSE: sends net profit for both directions per coin

run_test.sh

@@ -0,0 +1,4 @@
+#!/bin/bash
+cd /home/jack/Project/exchange-monitor-go
+# Redirect stderr to stdout so background mode captures everything
+./exchange-monitor 2>&1