fix(dkv): fix Kennzeichen matching and NaN/invalid km values in Excel export

Three issues fixed:

1. Kennzeichen normalization: DKV PDF extracts plates without hyphens
   ("GP JL 740E" vs CSV-imported "GP-JL 740E"). Added _normalizeKennzeichen()
   which strips hyphens, spaces, and dots before lookup — resolves vehicle
   master match failure that caused Marke/Modell/Fahrer to appear empty.

2. Empty-string NaN: parser used ?? '0' which doesn't catch empty strings,
   causing parseDE('') = NaN. Changed to || '0' for km, menge, and totals.

3. Invalid km values: EV charging rows from DKV have misaligned columns —
   km position contains a decimal price (e.g. 18.64 EUR or kWh). Added
   sanity check: non-integer km values are written as null (empty cell)
   instead of a misleading decimal. ExportRow.kilometerstand is now number|null.

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

apps/api/src/dkv/dkv.service.ts

@@ -579,15 +579,16 @@ export class DkvService {
     tenantId: string,
     vehicles: DkvVehicleBlock[],
     vehicleFormatString: string,
-  ): Promise<{ lieferdatum: string; fahrzeug: string; fahrer: string; ort: string; kilometerstand: number }[]> {
+  ): Promise<{ lieferdatum: string; fahrzeug: string; fahrer: string; ort: string; kilometerstand: number | null }[]> {
     // Batch load vehicle master to avoid N+1 queries
     const masters = await this.prisma.dkvVehicleMaster.findMany({ where: { tenantId } });
-    const masterMap = new Map(masters.map((m) => [m.kennzeichen, m]));
+    // Normalize keys: DKV PDF may omit hyphens or use spaces ("GP JL 740E" vs "GP-JL 740E")
+    const masterMap = new Map(masters.map((m) => [_normalizeKennzeichen(m.kennzeichen), m]));
 
-    const rows: { lieferdatum: string; fahrzeug: string; fahrer: string; ort: string; kilometerstand: number }[] = [];
+    const rows: { lieferdatum: string; fahrzeug: string; fahrer: string; ort: string; kilometerstand: number | null }[] = [];
 
     for (const vehicle of vehicles) {
-      const master = masterMap.get(vehicle.kennzeichen);
+      const master = masterMap.get(_normalizeKennzeichen(vehicle.kennzeichen));
 
       // For unknown plates: use empty string values for unknown fields
       const vehicleForFormat = {
@@ -601,12 +602,20 @@ export class DkvService {
       const fahrer = master?.fahrer ?? '';
 
       for (const tx of vehicle.transactions) {
+        // Only keep km values that are plausible odometer readings (whole numbers ≥ 0).
+        // Decimal values indicate a misaligned column (e.g. kWh or EUR from EV charging rows).
+        const rawKm = tx.kilometerstand;
+        const km: number | null =
+          Number.isNaN(rawKm) || !Number.isFinite(rawKm) || !Number.isInteger(rawKm)
+            ? null
+            : rawKm;
+
         rows.push({
           lieferdatum: tx.lieferdatum,
           fahrzeug,
           fahrer,
           ort: tx.ort,
-          kilometerstand: tx.kilometerstand,
+          kilometerstand: km,
         });
       }
     }
@@ -684,3 +693,12 @@ function _parseVehicleCsv(
 function _delay(ms: number): Promise<void> {
   return new Promise((resolve) => setTimeout(resolve, ms));
 }
+
+/**
+ * Normalize a Kennzeichen for fuzzy vehicle lookup.
+ * DKV PDF extraction may omit hyphens or use spaces as separators.
+ * Example: "GP JL 740E" == "GP-JL 740E" == "GPJL740E" after normalization.
+ */
+function _normalizeKennzeichen(k: string): string {
+  return k.toUpperCase().replace(/[\s\-\.]/g, '');
+}