style: 西门子 WinCC 工业风格重设计

- 左侧边栏导航替换顶部横向导航
- 色调改为石油蓝绿(#00a3be)，去除霓虹蓝
- 卡片头部加左侧色带 accent，去除圆角
- Badge 改为矩形工业风，全大写标签
- 按钮、输入框统一 2px radius
- 导航图标改为 SVG 几何图形替代纯文字缩写

frontend/src/assets/styles/variables.scss

@@ -1,31 +1,39 @@
-// ─── 色彩系统（与参考HTML完全一致）───
-$bg-primary:    #0d1117;
-$bg-secondary:  #161b22;
-$bg-card:       #1c2230;
-$bg-panel:      #212936;
-$bg-input:      #0d1117;
-$border:        #30363d;
-$border-active: #1f6feb;
+// ─── 工业暗色调色板（参考西门子 WinCC 风格）───
+$bg-base:      #0b0f16;
+$bg-primary:   #0f1420;
+$bg-secondary: #141a28;
+$bg-card:      #182030;
+$bg-panel:     #1c2538;
+$bg-hover:     #22304a;
+$bg-input:     #0b0f16;
 
-$text-primary:   #e6edf3;
-$text-secondary: #8b949e;
-$text-muted:     #6e7681;
+$border:       #263044;
+$border-light: #2e3d58;
+$border-active:#00a3be;
 
-$accent-blue:   #1f6feb;
-$accent-cyan:   #00b4d8;
-$accent-green:  #28a745;
-$accent-yellow: #f0a500;
-$accent-orange: #e05a00;
-$accent-red:    #da3633;
-$accent-purple: #8957e5;
+$text-primary:   #c8d6e8;
+$text-secondary: #6a82a0;
+$text-muted:     #3e5070;
 
-$sms-blue:      #0078d4;
-$sms-highlight: #00c8ff;
+// 西门子主色调 - 石油蓝绿
+$sms-teal:     #00a3be;
+$sms-teal-dim: #007a8c;
+$sms-blue:     #0066b3;
+$sms-blue-dim: #004d88;
 
-$status-run:   #28a745;
-$status-stop:  #6e7681;
-$status-warn:  #f0a500;
-$status-fault: #da3633;
+// 状态色
+$status-run:   #3db86e;
+$status-warn:  #d4880a;
+$status-fault: #c8322e;
+$status-stop:  #3e5070;
 
-$font-main: 'Segoe UI', 'Microsoft YaHei', sans-serif;
+$accent-green:  #3db86e;
+$accent-yellow: #d4880a;
+$accent-red:    #c8322e;
+$accent-cyan:   #00a3be;
+
+$font-main: 'Segoe UI', 'Microsoft YaHei UI', 'PingFang SC', sans-serif;
 $font-mono: 'Consolas', 'Courier New', monospace;
+
+// 向后兼容
+$sms-highlight: $sms-teal;