Restructure batch origins: nested entries per ingredient with Supplier/Farmer selects

Each BatchOrigin (spice) now has multiple BatchOriginEntry rows, replacing the flat
single-supplier/farmer fields. Lieferant and Landwirt are Select fields backed by
dedicated tables with inline create support. Migration preserves existing data.

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

app/Models/BatchOriginEntry.php

@@ -0,0 +1,25 @@
+<?php
+
+namespace App\Models;
+
+use Illuminate\Database\Eloquent\Model;
+
+class BatchOriginEntry extends Model
+{
+    protected $fillable = ['batch_origin_id', 'supplier_id', 'origin_country', 'farmer_id', 'notes'];
+
+    public function batchOrigin()
+    {
+        return $this->belongsTo(BatchOrigin::class);
+    }
+
+    public function supplier()
+    {
+        return $this->belongsTo(Supplier::class);
+    }
+
+    public function farmer()
+    {
+        return $this->belongsTo(Farmer::class);
+    }
+}