Fix Dutch model table names and seeder status values

- Add explicit $table property to all Eloquent models with Dutch names
- Fix pivot table names in belongsToMany relationships
- Fix seeder: use valid enum values for afhankelijkheden status

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

app/Models/Thema.php

@@ -11,6 +11,8 @@ class Thema extends Model
 {
     use SoftDeletes;
 
+    protected $table = 'themas';
+
     protected $fillable = [
         'naam',
         'beschrijving',