feat: add dd.MM.yyyy date formatting, default label number, and improve variable padding safety in label rendering

paperless-backend/src/label-print-agent/label-print-agent.service.ts

@@ -54,6 +54,7 @@ export class LabelPrintAgentService {
         const raw = fieldValues[field.name]; // erwartet YYYY-MM-DD
         const parts = raw.split('-');
         if (parts.length === 3) {
+          vars[field.name] = `${parts[2]}.${parts[1]}.${parts[0]}`; // dd.MM.yyyy
           vars[`${field.name}.year`] = parts[0];
           vars[`${field.name}.month`] = parts[1];
           vars[`${field.name}.day`] = parts[2];
@@ -165,6 +166,7 @@ export class LabelPrintAgentService {
       if (field.type === 'date' && fieldValues[field.name]) {
         const parts = fieldValues[field.name].split('-');
         if (parts.length === 3) {
+          vars[field.name] = `${parts[2]}.${parts[1]}.${parts[0]}`; // dd.MM.yyyy
           vars[`${field.name}.year`] = parts[0];
           vars[`${field.name}.month`] = parts[1];
           vars[`${field.name}.day`] = parts[2];
@@ -179,6 +181,7 @@ export class LabelPrintAgentService {
         this.logger.warn(`GET-URL fehlgeschlagen (${url}): ${err.message}`);
       }
     }
+    if (!('number' in vars)) vars['number'] = '1';
 
     return this.renderer.render(
       template.LabelLayout,

paperless-backend/src/label-print-agent/label-renderer.service.ts

@@ -19,8 +19,8 @@ function applyVars(template: string, vars: Record<string, string>): string {
     if (colonIdx !== -1) {
       const varName = key.slice(0, colonIdx);
       const width = parseInt(key.slice(colonIdx + 1), 10);
-      if (!isNaN(width) && varName in vars) {
-        return vars[varName].padStart(width, '0');
+      if (!isNaN(width)) {
+        return (vars[varName] ?? '').padStart(width, '0');
       }
     }
     return vars[key] ?? `{${key}}`;