Add Bot Activity admin panel: banned-IP view + recent events + emergency unban

Expose the botScore middleware's in-memory scoring/ban state to admins.
Previously state lived only in the store Map with no persistence or API — the
only visibility was tailing container logs.

- botScore: bounded ring buffer (300) recording scan/login-fail/honeypot and
  ban events (most-recent-first); listState() snapshot of all scored IPs;
  unban() to clear a single IP.
- New admin-only endpoints GET /admin/bot-activity and
  POST /admin/bot-activity/unban (RBAC admin gate, IP validated). Unban is
  activity-logged with the admin username.
- Bot Activity tab: currently-banned table with Unban, plus a recent-events
  feed, following the existing admin table patterns.
- Tests for the buffer, listState, and unban (guard lets an unbanned IP back
  through). README updated.

Read + emergency-unban only — no ban-add or weight-editing surface. Buffer is
in-memory, matching the store; not persisted.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

client/src/App.jsx

@@ -26,6 +26,7 @@ import WikiAdmin from './routes/admin/views/WikiAdmin.jsx'
 import HeroEditor from './routes/admin/views/HeroEditor.jsx'
 import SettingsAdmin from './routes/admin/views/SettingsAdmin.jsx'
 import ActivityAdmin from './routes/admin/views/ActivityAdmin.jsx'
+import BotActivityAdmin from './routes/admin/views/BotActivityAdmin.jsx'
 import UsersAdmin from './routes/admin/views/UsersAdmin.jsx'
 import AccountAdmin from './routes/admin/views/AccountAdmin.jsx'
 
@@ -71,6 +72,7 @@ export default function App() {
             <Route path="hero" element={<HeroEditor />} />
             <Route path="settings" element={<SettingsAdmin />} />
             <Route path="activity" element={<ActivityAdmin />} />
+            <Route path="bot-activity" element={<BotActivityAdmin />} />
             <Route path="users" element={<UsersAdmin />} />
             <Route path="account" element={<AccountAdmin />} />
             <Route path="*" element={<Navigate to="/admin" replace />} />