Let staff link their own characters + share the game-accounts UI

- Backend: /admin/shard/{link,accounts,roster/:account,vendors/:account} —
  staff self-service, reusing the player/shard controller (it keys off
  req.user.id, so the same handlers serve any logged-in role). Swagger under
  Admin · Account; spec regenerated.
- components/GameAccounts.jsx: the link-prompt + character-roster UI extracted
  into one reusable component parametrized by an api scope and a charTo(serial)
  route builder.
- PlayerCharacters now renders it (player scope → /player/char/:serial).
- Admin: "My Characters" nav item + /admin/characters (AdminCharacters) and
  /admin/characters/:serial (AdminCharacter, in-shell sheet), using the admin
  self-service scope. api.admin.shard.* added.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_011qPmpmVH1xGCiZoz9m9vW3

client/src/routes/admin/AdminLayout.jsx

@@ -79,6 +79,7 @@ const NAV = [
   },
   {
     items: [
+      { to: '/admin/characters', label: 'My Characters', icon: IconShard },
       { to: '/admin/account', label: 'Account', icon: IconUser },
     ],
   },
@@ -98,6 +99,7 @@ const TITLES = {
   '/admin/bot-activity': 'Web Bot Activity',
   '/admin/discord-bot': 'Discord Bot',
   '/admin/shard': 'Shard (uo-link)',
+  '/admin/characters': 'My Characters',
   '/admin/auth-providers': 'Authentication',
   '/admin/users': 'Users',
   '/admin/account': 'Account Security',
@@ -123,7 +125,11 @@ export default function AdminLayout() {
   const location = useLocation()
   const title =
     TITLES[location.pathname] ||
-    (location.pathname.startsWith('/admin/moderation') ? 'Moderation' : 'Admin')
+    (location.pathname.startsWith('/admin/moderation')
+      ? 'Moderation'
+      : location.pathname.startsWith('/admin/characters')
+        ? 'My Characters'
+        : 'Admin')
   // The hero canvas editor needs room — let it use the full content width.
   const wide = location.pathname === '/admin/hero'
   const modeDot = mode === 'live' ? 'var(--mode-live)' : 'var(--mode-maint)'