feat(PROJ-53): Konfigurierbare Listenanzahl pro Seite

- users.list_page_size (Default 25), PATCH /api/auth/preferences,
  Whitelist 25/50/100/200, Wert in login/me-Response
- Settings-UI mit Select, /search nutzt gespeicherte Seitengröße
- /api/search page_size serverseitig auf max. 500 gecappt

fix(PROJ-46): login_attempts-Migration nutzte s.db statt s.pool
(Backend kompilierte nicht)

feat(PROJ-50): DSGVO-Löschersuchen Backend (dsgvo_requests, Handler,
cc_addr/bcc_addr Indexerweiterung) — noch nicht QA'd/deployed

src/app/search/page.tsx

@@ -44,7 +44,7 @@ import { Label } from "@/components/ui/label";
 import { Switch } from "@/components/ui/switch";
 import { Bookmark, BookmarkPlus, Trash2 } from "lucide-react";
 
-const PAGE_SIZE = 25;
+const DEFAULT_PAGE_SIZE = 25;
 
 function formatBytes(bytes: number): string {
   if (bytes < 1024) return `${bytes} B`;
@@ -86,6 +86,8 @@ export default function SearchPage() {
   const { user, loading: authLoading } = useAuth();
   const router = useRouter();
 
+  const pageSize = user?.list_page_size ?? DEFAULT_PAGE_SIZE;
+
   const [query, setQuery] = useState("");
   const [fromFilter, setFromFilter] = useState("");
   const [toFilter, setToFilter] = useState("");
@@ -143,7 +145,7 @@ export default function SearchPage() {
           sort: sort !== "date_desc" ? sort : undefined,
           has_attachment: hasAttachment,
           page: p,
-          page_size: PAGE_SIZE,
+          page_size: pageSize,
         });
         setResults(res.hits || []);
         setTotal(res.total);
@@ -156,7 +158,7 @@ export default function SearchPage() {
         setSearching(false);
       }
     },
-    [query, fromFilter, toFilter, dateFrom, dateTo, sort, hasAttachment]
+    [query, fromFilter, toFilter, dateFrom, dateTo, sort, hasAttachment, pageSize]
   );
 
   // Superadmin has no mail access — redirect to admin dashboard
@@ -170,7 +172,7 @@ export default function SearchPage() {
   useEffect(() => {
     if (!user || user.role === "superadmin") return;
     setSearching(true);
-    searchEmails({ page: 1, page_size: PAGE_SIZE })
+    searchEmails({ page: 1, page_size: pageSize })
       .then((res) => {
         setResults(res.hits || []);
         setTotal(res.total);
@@ -182,7 +184,7 @@ export default function SearchPage() {
         setTotal(0);
       })
       .finally(() => setSearching(false));
-  }, [user]);
+  }, [user, pageSize]);
 
   function handleSubmit(e: React.FormEvent) {
     e.preventDefault();
@@ -339,7 +341,7 @@ export default function SearchPage() {
         date_to: s.query.date_to || undefined,
         has_attachment: s.query.has_attachment === "true" ? true : undefined,
         page: 1,
-        page_size: PAGE_SIZE,
+        page_size: pageSize,
       })
         .then((res) => {
           setResults(res.hits || []);
@@ -364,7 +366,7 @@ export default function SearchPage() {
     }
   }
 
-  const totalPages = Math.ceil(total / PAGE_SIZE);
+  const totalPages = Math.ceil(total / pageSize);
   const allSelected = results.length > 0 && results.every((h) => selected.has(h.id));
 
   return (

src/app/settings/page.tsx

@@ -16,10 +16,18 @@ import {
   DialogFooter,
 } from "@/components/ui/dialog";
 import { Badge } from "@/components/ui/badge";
+import {
+  Select,
+  SelectContent,
+  SelectItem,
+  SelectTrigger,
+  SelectValue,
+} from "@/components/ui/select";
 import { Server, Lock, Info } from "lucide-react";
 import {
   changePassword,
   changeEmail,
+  updatePreferences,
   getTOTPSetup,
   confirmTOTPSetup,
   disableTOTP,
@@ -28,7 +36,7 @@ import {
 } from "@/lib/api";
 
 export default function SettingsPage() {
-  const { user, loading } = useAuth();
+  const { user, loading, refresh } = useAuth();
 
   // ── Password state ────────────────────────────────────────────────────
   const [currentPw, setCurrentPw] = useState("");
@@ -59,6 +67,13 @@ export default function SettingsPage() {
   const [disableError, setDisableError] = useState("");
   const [disableLoading, setDisableLoading] = useState(false);
 
+  // ── Listenanzahl (Eintraege pro Seite) ────────────────────────────────
+  const [listPageSize, setListPageSize] = useState("25");
+  const [listPageSizeInitialized, setListPageSizeInitialized] = useState(false);
+  const [listPageSizeError, setListPageSizeError] = useState("");
+  const [listPageSizeSuccess, setListPageSizeSuccess] = useState("");
+  const [listPageSizeLoading, setListPageSizeLoading] = useState(false);
+
   // ── System info (FQDN + IMAP-Ports) ───────────────────────────────────
   const [systemInfo, setSystemInfo] = useState<SystemInfo | null>(null);
   const [systemInfoLoading, setSystemInfoLoading] = useState(true);
@@ -87,6 +102,12 @@ export default function SettingsPage() {
     setEmailInitialized(true);
   }
 
+  // Initialize list page size from user data once available
+  if (user && !listPageSizeInitialized) {
+    setListPageSize(String(user.list_page_size || 25));
+    setListPageSizeInitialized(true);
+  }
+
   // ── Handlers ──────────────────────────────────────────────────────────
 
   async function handleChangePassword(e: React.FormEvent) {
@@ -139,6 +160,24 @@ export default function SettingsPage() {
     }
   }
 
+  async function handleChangeListPageSize(value: string) {
+    setListPageSizeError("");
+    setListPageSizeSuccess("");
+    const parsed = Number(value);
+
+    setListPageSizeLoading(true);
+    try {
+      const result = await updatePreferences(parsed);
+      setListPageSize(String(result.list_page_size));
+      setListPageSizeSuccess("Eintraege pro Seite wurden gespeichert.");
+      await refresh();
+    } catch (err) {
+      setListPageSizeError(err instanceof Error ? err.message : "Fehler beim Speichern");
+    } finally {
+      setListPageSizeLoading(false);
+    }
+  }
+
   async function handleSetupTOTP() {
     setTotpError("");
     setTotpSuccess("");
@@ -312,6 +351,43 @@ export default function SettingsPage() {
           </CardContent>
         </Card>
 
+        {/* ── Card 2b: Listenanzahl ─────────────────────────────────────── */}
+        <Card>
+          <CardHeader>
+            <CardTitle>Listenansicht</CardTitle>
+          </CardHeader>
+          <CardContent className="space-y-4">
+            <div className="space-y-2">
+              <Label htmlFor="list-page-size">Eintraege pro Seite</Label>
+              <Select
+                value={listPageSize}
+                onValueChange={handleChangeListPageSize}
+                disabled={listPageSizeLoading}
+              >
+                <SelectTrigger id="list-page-size" className="w-40">
+                  <SelectValue />
+                </SelectTrigger>
+                <SelectContent>
+                  <SelectItem value="25">25</SelectItem>
+                  <SelectItem value="50">50</SelectItem>
+                  <SelectItem value="100">100</SelectItem>
+                  <SelectItem value="200">200</SelectItem>
+                </SelectContent>
+              </Select>
+            </div>
+            {listPageSizeError && (
+              <Alert variant="destructive">
+                <AlertDescription>{listPageSizeError}</AlertDescription>
+              </Alert>
+            )}
+            {listPageSizeSuccess && (
+              <Alert>
+                <AlertDescription>{listPageSizeSuccess}</AlertDescription>
+              </Alert>
+            )}
+          </CardContent>
+        </Card>
+
         {/* ── Card 3: Zwei-Faktor-Authentifizierung ────────────────────── */}
         <Card>
           <CardHeader>

src/hooks/useAuth.ts

@@ -58,5 +58,15 @@ export function useAuth(requireRole?: "admin" | "domain_admin" | "superadmin" |
     checkAuth();
   }, [checkAuth]);
 
-  return { user, loading };
+  const refresh = useCallback(async () => {
+    try {
+      const me = await getMe();
+      setCachedUser(me);
+      setUser(me);
+    } catch {
+      // ignore refresh errors, keep existing cached user
+    }
+  }, []);
+
+  return { user, loading, refresh };
 }

src/lib/api/index.ts

@@ -16,6 +16,7 @@ export {
   logout,
   changePassword,
   changeEmail,
+  updatePreferences,
   getUsers,
   createUser,
   updateUser,

src/lib/api/users.ts

@@ -26,6 +26,7 @@ export interface MeResponse {
   username: string;
   role: string;
   email: string;
+  list_page_size: number;
 }
 
 export interface CreateUserRequest {
@@ -82,6 +83,15 @@ export async function changeEmail(
   });
 }
 
+export async function updatePreferences(
+  listPageSize: number
+): Promise<{ ok: boolean; list_page_size: number }> {
+  return request<{ ok: boolean; list_page_size: number }>("/api/auth/preferences", {
+    method: "PATCH",
+    body: JSON.stringify({ list_page_size: listPageSize }),
+  });
+}
+
 // ── User management functions ─────────────────────────────────────────────────
 
 export async function getUsers(): Promise<User[]> {