Kontaktadresse: Neues Feld Position, Filter-Funktionen null-sicher, Projektnamen-Spalte entfernt

- Server: Neue Spalte position in Kontaktadresse-Modell (String(200), nullable)
- Server: Migration V01_04 (ALTER TABLE kontaktadressen ADD COLUMN position)
- Server: position in Geschäftslogik create/update aufgenommen
- Server: CLI-Musterdaten um Position ergänzt (Geschäftsführer, IT-Leiter etc.)
- Client: position in iKontaktadresse-Interface, View nach Firma, Columnmapper, Filter
- Client: Projektnamen-Spalte aus Kontaktadressenliste entfernt (steht in Überschrift)
- Client: Filter-Funktionen in allen Listen null-sicher (kunde, kontakt, projekt, kontaktadresse, call_log)

Generated by Mistral Vibe.
Co-Authored-By: Mistral Vibe <vibe@mistral.ai>

Client/Components/kontakt.ts

@@ -54,11 +54,11 @@ export const kontaktliste: m.ClosureComponent = (vnode) => {
     const filterFunction = (node: iTreenode, searchvalue: string): boolean => {
         let kontakt: iKontakt = node.nodevalue
         let searchLower = searchvalue.toLowerCase()
-        return kontakt.name.toLowerCase().includes(searchLower) ||
-               kontakt.position.toLowerCase().includes(searchLower) ||
-               kontakt.telefon.toLowerCase().includes(searchLower) ||
-               kontakt.email.toLowerCase().includes(searchLower) ||
-               kontakt.kunden_name.toLowerCase().includes(searchLower)
+        return (kontakt.name || "").toLowerCase().includes(searchLower) ||
+               (kontakt.position || "").toLowerCase().includes(searchLower) ||
+               (kontakt.telefon || "").toLowerCase().includes(searchLower) ||
+               (kontakt.email || "").toLowerCase().includes(searchLower) ||
+               (kontakt.kunden_name || "").toLowerCase().includes(searchLower)
     }
 
     return {