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/BeoSelector.tsx

@@ -20,7 +20,9 @@ export default function BeoSelector({ selected, onChange }: Props) {
   }, []);
 
   const selectedIds = new Set(selected.map((b) => b.ID));
-  const available = all.filter((b) => !selectedIds.has(b.ID));
+  const available = all
+    .filter((b) => !selectedIds.has(b.ID))
+    .sort((a, b) => a.Kuerzel.localeCompare(b.Kuerzel));
 
   function add(value: string) {
     const beo = all.find((b) => b.ID === parseInt(value));
@@ -39,7 +41,7 @@ export default function BeoSelector({ selected, onChange }: Props) {
             key={b.ID}
             className="inline-flex items-center gap-2 bg-blue-100 text-blue-800 text-base px-3 py-1.5 rounded-full"
           >
-            {b.Kuerzel} — {b.Name}
+            {b.Kuerzel}
             <button
               type="button"
               onClick={() => remove(b.ID)}