Adapt to existing beos table in database sternwarte

Column mapping: id, name/vorname, kürzel (with umlaut), pw instead of
the planned schema. DB_NAME changed to sternwarte. create_table.sql
no longer creates beos, only the three new logbuch tables.

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

app/login/actions.ts

@@ -1,7 +1,7 @@
 'use server';
 
 import { redirect } from 'next/navigation';
-import { verifyCredentials } from '@/lib/auth';
+import { verifyCredentials, getBeoDisplayName } from '@/lib/auth';
 import { createSession } from '@/lib/session';
 
 export async function login(
@@ -22,14 +22,14 @@ export async function login(
   }
 
   await createSession({
-    kuerzel: result.beo.Kuerzel,
-    beoId: result.beo.ID,
-    beoName: result.beo.Name,
+    kuerzel: result.beo.kürzel ?? kuerzel,
+    beoId: result.beo.id,
+    beoName: getBeoDisplayName(result.beo),
     mustChangePassword: result.beo.MustChangePassword === 1,
     isAuthenticated: true,
   });
 
-  if (result.beo.MustChangePassword === 1) {
+  if (result.beo.MustChangePassword === 1 || !result.beo.pw) {
     redirect('/change-password');
   }