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>

types/logbuch.ts

@@ -1,11 +1,12 @@
 export type Kuppel = 'West' | 'Ost' | 'Süd' | 'Pluto';
-export type ArtFuehrung = 'RF' | 'SF' | 'BEOS' | 'SonF' | 'TD' | 'Beob' | 'ToT' | 'Sonst';
+export type ArtFuehrung = 'RF' | 'SF' | 'PrF' | 'BEOS' | 'SonF' | 'TD' | 'Beob' | 'ToT' | 'Sonst';
 
 export const KUPPELN: Kuppel[] = ['West', 'Ost', 'Süd', 'Pluto'];
 
 export const ARTEN_MAP: Record<ArtFuehrung, string> = {
   RF:   'Reguläre Führung',
   SF:   'Sonderführung',
+  PrF:  'Private Führung',
   BEOS: 'BEO-Sitzung',
   SonF: 'Sonnenführung',
   TD:   'Technischer Dienst',