feat(home): add help center quick operation link

- Add helpCenter.svg and helpCenter_active.svg menu icons for help center navigation
- Add "Help Center" translation strings to English and Chinese i18n files
- Update QuickOperation component to include help center as fourth quick operation
- Implement external link handler that opens help documentation based on current language (zh or en)
- Change grid layout from 3 columns to 4 columns to accommodate new help center card
- Add file header documentation to QuickOperation component
- Help center link redirects to https://docs.redbearai.com/s/{lang}-memorybear with language-specific routing

web/src/assets/images/menu/helpCenter.svg

@@ -0,0 +1,14 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<svg width="16px" height="16px" viewBox="0 0 16 16" version="1.1" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink">
+    <title>使用帮助备份</title>
+    <g id="v0.2.0" stroke="none" stroke-width="1" fill="none" fill-rule="evenodd">
+        <g id="首页" transform="translate(-51, -358)" stroke="#5F6266">
+            <g id="使用帮助备份" transform="translate(51, 358)">
+                <g id="编组-35" transform="translate(2, 1.5)">
+                    <path d="M6.13163525,1.97938144 L10.3064533,1.97938144 C11.2417733,1.97938144 12,2.70634106 12,3.6030912 L12,10.3762902 C12,11.2730404 11.2417733,12 10.3064533,12 L1.69354673,12 C0.758226699,12 0,11.2730404 0,10.3762902 L0,3.6030912 C0,2.70634106 0.758226699,1.97938144 1.69354673,1.97938144 L2.02448435,1.97938144 L2.02448435,1.97938144" id="路径"></path>
+                    <path d="M3.52033177,0.78470905 L6.09032258,1.97938144 L6.09032258,1.97938144 L6.09032258,11.8762887 L2.51918436,10.2162282 C2.10022604,10.0214734 1.83225806,9.6014016 1.83225806,9.13938916 L1.83225806,1.86154804 C1.83225806,1.2057099 2.36391992,0.674048044 3.01975806,0.674048044 C3.19268295,0.674048044 3.36352144,0.711815028 3.52033177,0.78470905 Z" id="矩形" stroke-linejoin="round"></path>
+                </g>
+            </g>
+        </g>
+    </g>
+</svg>

web/src/assets/images/menu/helpCenter_active.svg

@@ -0,0 +1,14 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<svg width="16px" height="16px" viewBox="0 0 16 16" version="1.1" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink">
+    <title>使用帮助</title>
+    <g id="v0.2.0" stroke="none" stroke-width="1" fill="none" fill-rule="evenodd">
+        <g id="首页" transform="translate(-24, -358)" stroke="#212332">
+            <g id="使用帮助" transform="translate(24, 358)">
+                <g id="编组-35" transform="translate(2, 1.5)">
+                    <path d="M6.13163525,1.97938144 L10.3064533,1.97938144 C11.2417733,1.97938144 12,2.70634106 12,3.6030912 L12,10.3762902 C12,11.2730404 11.2417733,12 10.3064533,12 L1.69354673,12 C0.758226699,12 0,11.2730404 0,10.3762902 L0,3.6030912 C0,2.70634106 0.758226699,1.97938144 1.69354673,1.97938144 L2.02448435,1.97938144 L2.02448435,1.97938144" id="路径"></path>
+                    <path d="M3.52033177,0.78470905 L6.09032258,1.97938144 L6.09032258,1.97938144 L6.09032258,11.8762887 L2.51918436,10.2162282 C2.10022604,10.0214734 1.83225806,9.6014016 1.83225806,9.13938916 L1.83225806,1.86154804 C1.83225806,1.2057099 2.36391992,0.674048044 3.01975806,0.674048044 C3.19268295,0.674048044 3.36352144,0.711815028 3.52033177,0.78470905 Z" id="矩形" stroke-linejoin="round"></path>
+                </g>
+            </g>
+        </g>
+    </g>
+</svg>