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/views/AdminCharacters.jsx

@@ -0,0 +1,15 @@
+import GameAccounts from '../../../components/GameAccounts.jsx'
+import { api } from '../../../api/client.js'
+
+// Staff link their OWN in-game account and view their characters — the same
+// shared component players use, pointed at the staff self-service endpoints.
+export default function AdminCharacters() {
+  return (
+    <section style={{ maxWidth: 760 }}>
+      <p className="sans" style={{ marginTop: 0, marginBottom: 22, color: 'var(--muted)', fontSize: '0.92rem', lineHeight: 1.6 }}>
+        Link your own game account to view your characters, stats, skills and vendors.
+      </p>
+      <GameAccounts scope={api.admin.shard} charTo={(serial) => `/admin/characters/${serial}`} />
+    </section>
+  )
+}