Remove RecoveryBanner component and dead onCrashDetected code

- Delete RecoveryBanner.tsx component and its test
- Remove RecoveryBanner from MainLayout
- Remove onCrashDetected prop from ActivateJailDialog, JailsTab
- Remove fetchPendingRecovery, rollbackJail API functions
- Remove configJailRollback, configPendingRecovery endpoints
- Remove PendingRecovery type

frontend/src/layouts/MainLayout.tsx

@@ -33,7 +33,6 @@ import { NavLink, Outlet, useNavigate } from "react-router-dom";
 import { useAuth } from "../providers/AuthProvider";
 import { useServerStatus } from "../hooks/useServerStatus";
 import { useBlocklistStatus } from "../hooks/useBlocklist";
-import { RecoveryBanner } from "../components/common/RecoveryBanner";
 
 // ---------------------------------------------------------------------------
 // Styles
@@ -336,8 +335,6 @@ export function MainLayout(): React.JSX.Element {
             </MessageBar>
           </div>
         )}
-        {/* Recovery banner — shown when fail2ban crashed after a jail activation */}
-        <RecoveryBanner />
         {/* Blocklist import error warning — shown when the last scheduled import had errors */}
         {blocklistHasErrors && (
           <div className={styles.warningBar} role="alert">