feat: 新增二级菜单子导航系统（SubNav + redirectMenu）

- 新增 SubNav 组件：Navbar 下方水平子导航条，展示当前二级菜单下的三级页面，支持滚动和下拉分组
- 新增 redirectMenu 页面：点击二级菜单时卡片式展示子页面列表
- SidebarItem 深度 >=1 时改为叶子节点渲染（小圆点标记），激活高亮回退到二级菜单
- Navbar 布局重构为 Flexbox，面包屑/SubNav 根据场景切换
- 新增 productionLine Vuex 模块，轧辊研磨页改为 store 方式读取产线数据
- Sidebar activeMenu 逻辑增强：自动定位当前页所属二级菜单

klp-ui/src/layout/components/Navbar.vue

@@ -2,7 +2,8 @@
   <div class="navbar">
     <hamburger id="hamburger-container" :is-active="sidebar.opened" class="hamburger-container" @toggleClick="toggleSideBar" />
 
-    <breadcrumb id="breadcrumb-container" class="breadcrumb-container" v-if="!topNav"/>
+    <breadcrumb id="breadcrumb-container" class="breadcrumb-container" v-show="topNav || !showSubNav"/>
+    <sub-nav id="subnav-container" class="subnav-container" v-if="!topNav" @has-items="showSubNav = $event"/>
     <top-nav id="topmenu-container" class="topmenu-container" v-if="topNav"/>
 
     <div class="right-menu">
@@ -52,6 +53,7 @@
 import { mapGetters } from 'vuex'
 import Breadcrumb from '@/components/Breadcrumb'
 import TopNav from '@/components/TopNav'
+import SubNav from './SubNav'
 import Hamburger from '@/components/Hamburger'
 import Screenfull from '@/components/Screenfull'
 // import SizeSelect from '@/components/SizeSelect'
@@ -64,6 +66,7 @@ export default {
   components: {
     Breadcrumb,
     TopNav,
+    SubNav,
     Hamburger,
     Screenfull,
     // SizeSelect,
@@ -74,7 +77,8 @@ export default {
   data() {
     return {
       hasWarning: false,
-      warningTimer: null
+      warningTimer: null,
+      showSubNav: true
     }
   },
   computed: {
@@ -153,6 +157,8 @@ export default {
   height: 50px;
   overflow: hidden;
   position: relative;
+  display: flex;
+  align-items: center;
   // 金属质感渐变背景
   // background: #454c51;
   // border-bottom: 1px solid #8d939b;
@@ -162,7 +168,7 @@ export default {
   .hamburger-container {
     line-height: 46px;
     height: 100%;
-    float: left;
+    flex-shrink: 0;
     cursor: pointer;
     transition: all .3s ease;
     -webkit-tap-highlight-color: transparent;
@@ -177,10 +183,16 @@ export default {
   }
 
   .breadcrumb-container {
-    float: left;
+    flex-shrink: 0;
     padding-left: 15px;
   }
 
+  .subnav-container {
+    flex: 1;
+    min-width: 0;
+    padding-left: 8px;
+  }
+
   .topmenu-container {
     position: absolute;
     left: 50px;
@@ -192,7 +204,8 @@ export default {
   }
 
   .right-menu {
-    float: right;
+    flex-shrink: 0;
+    margin-left: auto;
     height: 100%;
     line-height: 50px;