feat(admin): view a user's shard footprint at /admin/users/:id

Add a "View" action beside Edit in the users table that opens a dedicated,
read-only page showing everything the uo-link shard knows about a user,
scoped to their linked game accounts: character rosters, currently-online
characters, houses (IDOC-first), and recent vendor sales.

Backend (admin-only, under the existing /users adminOnly gate):
- GET /admin/users/:id — single sanitized user (page is deep-linkable)
- GET /admin/users/:id/shard/{accounts,sales,houses,online}
- shardState: listHousesByAccounts / listOnlineByAccounts (+ model shapers)
- Extract salesForAccounts into utils/shardSales; reuse in player getSales
- Live rosters reuse the existing admin-bypass /admin/shard/* endpoints,
  so no new routes for roster/vendors/char

Frontend:
- UserDetail page reusing CharacterStats / GameAccounts / VendorSales
- GameAccounts gains a readOnly prop (drops link form + self-voice copy)
- api.admin.getUser + api.admin.userShard(id) scope; route + layout title

Tests: adminUserShard.test.js (404, account scoping, empty accounts,
salesForAccounts cap/filter). Full server suite 164 pass; client builds.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_0114TpmrNW4wNXsHq5CR72jQ

client/src/api/client.js

@@ -159,9 +159,23 @@ export const api = {
     botActivity: () => req('/admin/bot-activity'),
     unbanIp: (ip) => req('/admin/bot-activity/unban', { method: 'POST', body: { ip } }),
     listUsers: () => req('/admin/users'),
+    getUser: (id) => req(`/admin/users/${id}`),
     createUser: (data) => req('/admin/users', { method: 'POST', body: data }),
     updateUser: (id, data) => req(`/admin/users/${id}`, { method: 'PUT', body: data }),
     deleteUser: (id) => req(`/admin/users/${id}`, { method: 'DELETE' }),
+    // A single user's shard (uo-link) footprint, scoped to their linked accounts.
+    // accounts/sales/houses/online are user-scoped endpoints; roster/vendors/char
+    // reuse the admin-bypass /admin/shard/* endpoints (which already read any
+    // account) so the shared GameAccounts component works unchanged.
+    userShard: (id) => ({
+      accounts: () => req(`/admin/users/${id}/shard/accounts`),
+      roster: (account) => req(`/admin/shard/roster/${encodeURIComponent(account)}`),
+      vendors: (account) => req(`/admin/shard/vendors/${encodeURIComponent(account)}`),
+      char: (serial) => req(`/admin/shard/char/${encodeURIComponent(serial)}`),
+      sales: () => req(`/admin/users/${id}/shard/sales`),
+      houses: () => req(`/admin/users/${id}/shard/houses`),
+      online: () => req(`/admin/users/${id}/shard/online`),
+    }),
 
     // ----- moderation dashboard (admin + moderator) -----
     modSummary: () => req('/admin/moderation/stats/summary'),