feat(docs): nest Core-flow under GeneralUpdate.Core category with short label (#134)

- Wrap GeneralUpdate.Core as a collapsible category in sidebar
- Nest Core-flow as sub-item (execution-flow inside Core)
- Set sidebar_label: '执行流程详解' (zh) / 'Execution Flow' (en)

Co-authored-by: Claude <noreply@anthropic.com>

Author: JusterZhu

website/docs/doc/Core-flow.md

@@ -1,5 +1,6 @@
 ---
 sidebar_position: 4
+sidebar_label: 执行流程详解
 ---
 
 # GeneralUpdate.Core — 执行流程详解

website/i18n/en/docusaurus-plugin-content-docs/current/doc/Core-flow.md

@@ -1,5 +1,6 @@
 ---
 sidebar_position: 4
+sidebar_label: Execution Flow
 ---
 
 # GeneralUpdate.Core — Execution Flow Deep Dive

website/sidebars.js

@@ -34,8 +34,14 @@ const sidebars = {
       collapsed: false,
       items: [
         'doc/Component Introduction',
-        'doc/GeneralUpdate.Core',
-        'doc/Core-flow',
+        {
+          type: 'category',
+          label: 'GeneralUpdate.Core',
+          collapsible: true,
+          collapsed: true,
+          link: { type: 'doc', id: 'doc/GeneralUpdate.Core' },
+          items: ['doc/Core-flow'],
+        },
         'doc/GeneralUpdate.Bowl',
         'doc/GeneralUpdate.Differential',
         'doc/GeneralUpdate.Drivelution',