refactor(docs): remove legacy documentation pages and admin manual assets

Deleted all admin and integration documentation pages from /docs routes, including admin manual PNG assets. Removed DocCode, DocFigure, DocsSidebar, and DocsShell components along with their associated navigation configurations. Eliminated "Related Docs" menu item from admin toolbar. Cleaned up unused documentation layout files and redirect pages across admin-manual, integration-guide, and docs sections.

src/i18n/locales/en/config.json

@@ -53,8 +53,6 @@
   "hub": {
     "description": "Jump to play rules, odds & rebate, jackpot, and risk cap by domain. The sidebar provides direct links; this page is an overview.",
     "integrationDesc": "site_code, JWT secrets, partner wallet URL, iframe allowlist",
-    "integrationGuideDesc": "SSO and wallet integration document for client engineering teams, with index, examples, and test flow",
-    "integrationGuideTitle": "Client integration guide",
     "integrationTitle": "Integration sites",
     "jackpotDesc": "Pool parameters and ledger records",
     "jackpotTitle": "Jackpot",
@@ -66,9 +64,6 @@
     "riskCapTitle": "Risk cap rules",
     "title": "Operations configuration"
   },
-  "integrationGuide": {
-    "title": "Lottery client integration guide"
-  },
   "integrationSites": {
     "adminAccountCreated": "Created site admin account {{username}}",
     "adminAccountSectionDescription": "Creating a site will also create one admin account bound to that site.",