fix(events): typed-DELETE confirmation for bulk delete (#417)

The bulk-delete modal previously used a password input as a confirmation
gate, with an Enter-to-submit handler. Windows Hello / passkey flows
that target password fields were able to autofill and synthesise an
Enter keystroke, which submitted the form and triggered the destructive
delete without an explicit click on the red Delete button (Rekoo's
report in #417).

Replace the password gate with a GitHub-style typed-literal pattern:
the user types the literal "DELETE" (English, case-sensitive) into a
plain text input. The Delete button stays disabled until the input
matches, and there is no Enter-to-submit handler — only an explicit
click on the red button proceeds. Plain text inputs aren't subject to
password autofill or passkey ceremony so the auto-submit class of bug
is gone.

Server side, drop the bcrypt password verify on /admin/events/bulk-delete
and the related INVALID_PASSWORD response. The server's auth boundary
remains adminAuth + requirePermission('events.delete'); this matches
DELETE /admin/events/:id which has never required a re-entered password.
The client-side typed gate is the safeguard against accidental clicks.

i18n: drop password-related keys, add confirmLabel + confirmHelp across
en, de, nl, pt, ru. The literal "DELETE" stays English in all locales
to keep the gesture immune to translation drift and unambiguous.

Verified locally: typed-DELETE sanity spec covers the gate (wrong case
disabled, correct enables, Enter-on-input no-ops, click submits, events
deleted). Existing 03-bulk-archive smoke remains green.

frontend/src/components/admin/BulkDeleteModal.tsx

@@ -1,19 +1,21 @@
 import React, { useState } from 'react';
-import { Trash2, AlertTriangle, X, Lock, Eye, EyeOff, Loader2 } from 'lucide-react';
+import { Trash2, AlertTriangle, X, Loader2 } from 'lucide-react';
 import { useTranslation } from 'react-i18next';
 import { Button, Card, Input } from '../common';
 import type { Event } from '../../types';
 
+// The exact literal a user must type to confirm bulk deletion. Kept English
+// across locales (matching GitHub's repo-deletion pattern) so it can never
+// be interpreted as autofillable text or be triggered by passkey/Windows
+// Hello flows on a password field — see issue #417.
+const CONFIRM_LITERAL = 'DELETE';
+
 interface BulkDeleteModalProps {
   isOpen: boolean;
   onClose: () => void;
-  onConfirm: (password: string) => Promise<void>;
+  onConfirm: () => Promise<void>;
   selectedEvents: Event[];
   isLoading?: boolean;
-  /** Set when the server responded 401 INVALID_PASSWORD; surfaces inline. */
-  passwordError?: string | null;
-  /** Clear the inline password error when the user starts typing again. */
-  onPasswordErrorClear?: () => void;
 }
 
 export const BulkDeleteModal: React.FC<BulkDeleteModalProps> = ({
@@ -22,25 +24,18 @@ export const BulkDeleteModal: React.FC<BulkDeleteModalProps> = ({
   onConfirm,
   selectedEvents,
   isLoading = false,
-  passwordError = null,
-  onPasswordErrorClear,
 }) => {
   const { t } = useTranslation();
-  const [password, setPassword] = useState('');
-  const [showPassword, setShowPassword] = useState(false);
+  const [confirmText, setConfirmText] = useState('');
 
   if (!isOpen) return null;
 
   const count = selectedEvents.length;
+  const confirmed = confirmText === CONFIRM_LITERAL;
 
   const handleSubmit = async () => {
-    if (!password || isLoading) return;
-    await onConfirm(password);
-  };
-
-  const handlePasswordChange = (val: string) => {
-    setPassword(val);
-    if (passwordError && onPasswordErrorClear) onPasswordErrorClear();
+    if (!confirmed || isLoading) return;
+    await onConfirm();
   };
 
   return (
@@ -61,7 +56,6 @@ export const BulkDeleteModal: React.FC<BulkDeleteModalProps> = ({
             </button>
           </div>
 
-          {/* Processing-state banner replaces the warning + form when in flight. */}
           {isLoading ? (
             <div className="py-8 text-center">
               <Loader2 className="w-8 h-8 mx-auto mb-3 animate-spin text-red-600 dark:text-red-400" />
@@ -90,28 +84,22 @@ export const BulkDeleteModal: React.FC<BulkDeleteModalProps> = ({
 
               <div className="mb-6">
                 <Input
-                  type={showPassword ? 'text' : 'password'}
-                  label={t('events.bulkDelete.passwordLabel', 'Re-enter your password to confirm')}
-                  value={password}
-                  onChange={(e) => handlePasswordChange(e.target.value)}
-                  placeholder={t('events.bulkDelete.passwordPlaceholder', 'Your admin password')}
-                  helperText={t('events.bulkDelete.passwordHelp', 'We require your password as a safeguard against accidental bulk deletions.')}
-                  error={passwordError || undefined}
-                  leftIcon={<Lock className="w-5 h-5" />}
-                  rightIcon={
-                    <button
-                      type="button"
-                      onClick={() => setShowPassword(!showPassword)}
-                      className="p-1"
-                      tabIndex={-1}
-                    >
-                      {showPassword ? <EyeOff className="w-5 h-5" /> : <Eye className="w-5 h-5" />}
-                    </button>
-                  }
+                  type="text"
+                  label={t(
+                    'events.bulkDelete.confirmLabel',
+                    'Type {{literal}} to confirm',
+                    { literal: CONFIRM_LITERAL }
+                  )}
+                  value={confirmText}
+                  onChange={(e) => setConfirmText(e.target.value)}
+                  placeholder={CONFIRM_LITERAL}
+                  helperText={t(
+                    'events.bulkDelete.confirmHelp',
+                    'A typed confirmation prevents accidental deletions and isn\'t affected by browser autofill or passkey shortcuts.'
+                  )}
                   autoFocus
-                  onKeyDown={(e) => {
-                    if (e.key === 'Enter' && password) handleSubmit();
-                  }}
+                  autoComplete="off"
+                  spellCheck={false}
                 />
               </div>
 
@@ -126,7 +114,7 @@ export const BulkDeleteModal: React.FC<BulkDeleteModalProps> = ({
                 <Button
                   variant="primary"
                   onClick={handleSubmit}
-                  disabled={!password || isLoading}
+                  disabled={!confirmed || isLoading}
                   leftIcon={<Trash2 className="w-4 h-4" />}
                   className="bg-red-600 hover:bg-red-700 focus:ring-red-500 text-white"
                 >