Various UX improvements and bug fixes

- Fix mustChangePassword session flag for users with pw=NULL
- Add PrF (Private Führung) as new ArtFuehrung type
- Split datetime-local into separate date + TimePicker5 (5-min steps, auto-repeat)
- Responsive Beginn/Ende layout: stacked on mobile, inline on desktop
- Sort BEOs alphabetically by Kürzel in selector
- Title shows active kuppel; hide user display in header
- Selected BEOs show Kürzel only (name stays in dropdown)
- Session timeout reduced to 1 hour
- Add CLAUDE.md

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

components/LogbuchForm.tsx

@@ -6,6 +6,7 @@ import { ARTEN, ARTEN_MAP } from '@/types/logbuch';
 import BeoSelector from './BeoSelector';
 import ObjektSelector from './ObjektSelector';
 import CustomSelect from './CustomSelect';
+import TimePicker5 from './TimePicker5';
 
 interface Props {
   kuppel: Kuppel;
@@ -19,24 +20,39 @@ function toLocalDatetimeValue(isoOrDatetime: string): string {
   return isoOrDatetime.slice(0, 16);
 }
 
-function snapTo15(value: string): string {
+function snapTo5(value: string): string {
   if (!value) return value;
-  const d = new Date(value);
+  // Fix 4-digit years that are actually < 100 (e.g. "0024" → "2024")
+  const fixed = value.replace(/^(\d{4})(-.+)$/, (_, y, rest) => {
+    const year = parseInt(y, 10);
+    return (year < 100 ? String(year + 2000) : y) + rest;
+  });
+  const d = new Date(fixed);
   if (isNaN(d.getTime())) return value;
-  const rem = d.getMinutes() % 15;
-  if (rem !== 0) {
-    d.setMinutes(d.getMinutes() + (15 - rem));
-    d.setSeconds(0);
-  }
+  d.setMinutes(Math.round(d.getMinutes() / 5) * 5);
+  d.setSeconds(0);
   const pad = (n: number) => String(n).padStart(2, '0');
   return `${d.getFullYear()}-${pad(d.getMonth() + 1)}-${pad(d.getDate())}T${pad(d.getHours())}:${pad(d.getMinutes())}`;
 }
 
+function snapTimeTo5(time: string): string {
+  if (!time) return time;
+  const [hStr, mStr] = time.split(':');
+  const h = parseInt(hStr, 10);
+  const m = parseInt(mStr, 10);
+  if (isNaN(h) || isNaN(m)) return time;
+  const snappedM = Math.round(m / 5) * 5;
+  const finalH = snappedM >= 60 ? (h + 1) % 24 : h;
+  const finalM = snappedM >= 60 ? 0 : snappedM;
+  const pad = (n: number) => String(n).padStart(2, '0');
+  return `${pad(finalH)}:${pad(finalM)}`;
+}
+
 function nowLocalDatetime(): string {
   const now = new Date();
   const pad = (n: number) => String(n).padStart(2, '0');
   const raw = `${now.getFullYear()}-${pad(now.getMonth() + 1)}-${pad(now.getDate())}T${pad(now.getHours())}:${pad(now.getMinutes())}`;
-  return snapTo15(raw);
+  return snapTo5(raw);
 }
 
 const NO_OBJEKTE_ARTEN: ArtFuehrung[] = ['BEOS', 'TD'];
@@ -188,32 +204,51 @@ export default function LogbuchForm({ kuppel, currentUserBeo, editEntry, onSaved
         />
       </div>
 
-      {/* Beginn / Ende / Besucher — eine Zeile */}
-      <div className="flex flex-wrap gap-3 items-end">
-        <div className="flex-1 min-w-0">
+      {/* Beginn / Ende / Besucher */}
+      <div className="flex flex-col sm:flex-row gap-3 sm:items-end">
+        <div className="w-full sm:flex-1">
           <label className={labelCls}>Beginn</label>
-          <input
-            type="datetime-local"
-            value={beginn}
-            onChange={(e) => setBeginn(snapTo15(e.target.value))}
-            required
-            step={900}
-            className="w-full px-2 py-2 border-2 border-gray-400 rounded-lg bg-white text-sm focus:border-blue-500 focus:outline-none"
-          />
+          <div className="flex gap-2">
+            <input
+              type="date"
+              value={beginn.slice(0, 10)}
+              onChange={(e) => {
+                if (!e.target.value) return;
+                setBeginn(e.target.value + 'T' + (beginn.slice(11, 16) || '00:00'));
+                setEnde(e.target.value + 'T' + (ende.slice(11, 16) || '00:00'));
+              }}
+              required
+              className="flex-1 px-2 py-2 border-2 border-gray-400 rounded-lg bg-white text-sm focus:border-blue-500 focus:outline-none"
+            />
+            <TimePicker5
+              value={beginn.slice(11, 16)}
+              onChange={(t) => setBeginn(beginn.slice(0, 10) + 'T' + t)}
+              className="w-24"
+            />
+          </div>
         </div>
-        <div className="flex-1 min-w-0">
+        <div className="w-full sm:flex-1">
           <label className={labelCls}>Ende</label>
-          <input
-            type="datetime-local"
-            value={ende}
-            onChange={(e) => setEnde(snapTo15(e.target.value))}
-            required
-            step={900}
-            className="w-full px-2 py-2 border-2 border-gray-400 rounded-lg bg-white text-sm focus:border-blue-500 focus:outline-none"
-          />
+          <div className="flex gap-2">
+            <input
+              type="date"
+              value={ende.slice(0, 10)}
+              onChange={(e) => {
+                if (!e.target.value) return;
+                setEnde(e.target.value + 'T' + (ende.slice(11, 16) || '00:00'));
+              }}
+              required
+              className="flex-1 px-2 py-2 border-2 border-gray-400 rounded-lg bg-white text-sm focus:border-blue-500 focus:outline-none"
+            />
+            <TimePicker5
+              value={ende.slice(11, 16)}
+              onChange={(t) => setEnde(ende.slice(0, 10) + 'T' + t)}
+              className="w-24"
+            />
+          </div>
         </div>
         {showBesucher && (
-          <div className="shrink-0">
+          <div className="sm:shrink-0">
             <label className={labelCls}>Besucher</label>
             <input
               type="number"