chore: startup script with port detection and auto-cleanup

./start.sh:
1. Detect if port 8888 is in use → kill gracefully, force if needed
2. Verify port free, rebuild if source changed, start in background
3. Wait up to 10s for readiness confirmation

start.sh

@@ -0,0 +1,55 @@
+#!/usr/bin/env bash
+# exchange-monitor 启动脚本
+# 自动检测端口占用并清理旧进程
+
+set -e
+
+cd "$(dirname "$0")"
+PORT=8888
+BIN="./exchange-monitor"
+LOG="exchange-monitor.log"
+
+# 检查端口占用，释放旧进程
+PID=$(ss -tlnp 2>/dev/null | grep ":$PORT " | sed -n 's/.*pid=\([0-9]*\).*/\1/p')
+if [ -n "$PID" ]; then
+    echo "[start] Port $PORT 被 PID=$PID 占用，尝试优雅停止..."
+    kill "$PID" 2>/dev/null || true
+    sleep 1
+    # 强制清理
+    if kill -0 "$PID" 2>/dev/null; then
+        echo "[start] 强制终止 PID=$PID..."
+        kill -9 "$PID" 2>/dev/null || true
+        sleep 1
+    fi
+fi
+
+# 确认端口空闲
+if ss -tlnp 2>/dev/null | grep -q ":$PORT "; then
+    echo "[start] ERROR: 端口 $PORT 仍被占用，放弃启动"
+    exit 1
+fi
+
+# 编译（如果源码有变更）
+if [ ! -x "$BIN" ] || [ "$(find . -name '*.go' -newer "$BIN" 2>/dev/null | head -1)" ]; then
+    echo "[start] 编译新二进制..."
+    go build -o "$BIN" . 2>&1
+fi
+
+# 启动
+echo "[start] 启动 exchange-monitor (端口 $PORT)..."
+nohup "$BIN" >> "$LOG" 2>&1 &
+PID=$!
+echo "[start] PID=$PID"
+
+# 等待就绪
+for i in $(seq 1 10); do
+    if ss -tlnp 2>/dev/null | grep -q ":$PORT "; then
+        echo "[start] 就绪 (${i}s)"
+        echo "[start] http://localhost:$PORT"
+        exit 0
+    fi
+    sleep 1
+done
+
+echo "[start] 启动超时（10s），请检查日志: tail -f $LOG"
+exit 1