Refactor infrastructure scripts and add mock hardware support

Changes:
- Refactor project scripts for better dev/prod workflow separation
- Add mock_hardware.py for local development without real hardware
- Add Makefile for common commands
- Add .env.example for environment variable reference
- Split scripts into dev-backend.sh, dev-frontend.sh, prod-backend.sh
- Add stop.sh for clean shutdown

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

scripts/stop.sh

@@ -0,0 +1,34 @@
+#!/bin/bash
+# ============================================================
+# stop.sh - 停止开发服务
+# 用法: ./scripts/stop.sh
+# 说明: 停止 Flask 和 Next.js 开发服务器
+# ============================================================
+set -e
+
+echo "=========================================="
+echo "  停止开发服务"
+echo "=========================================="
+echo ""
+
+# 停止 Flask
+if pgrep -f "python.*app.py" > /dev/null 2>&1; then
+    echo "停止 Flask..."
+    pkill -f "python.*app.py" || true
+    pkill -f "uv run .*python app.py" || true
+    echo "  ✓ Flask 已停止"
+else
+    echo "  - Flask 未运行"
+fi
+
+# 停止 Next.js
+if pgrep -f "next dev" > /dev/null 2>&1; then
+    echo "停止 Next.js..."
+    pkill -f "next dev" || true
+    echo "  ✓ Next.js 已停止"
+else
+    echo "  - Next.js 未运行"
+fi
+
+echo ""
+echo "完成"