refactor(web): unify settings dialogs into single dialog with sidebar

Merge API integration, model settings, account settings and storage
analysis into one SettingsDialog with a shadcn inner sidebar for
section switching. Preserve existing ?action= query-param deep links
(showModelSettings / showAccountSettings / showApiIntegrationSettings /
showStorageAnalysis) by mapping each to a section. Extract reusable
panels and keep ModelsDialog as a thin wrapper for the dynamic-form
model picker.

web/src/i18n/locales/zh-Hans.ts

@@ -1328,6 +1328,9 @@ const zhHans = {
     boxSessionCreated: '创建时间',
     boxSessionLastUsed: '最后使用',
   },
+  settingsDialog: {
+    title: '设置',
+  },
   storageAnalysis: {
     title: '存储分析',
     description: '查看存储占用和可清理文件',