Remove unused model constants

- Company: COMPANY_LEVEL, CUSTOMER_LEVEL (never referenced)
- Payment: all 5 PAYMENT_MODE_* constants (never referenced)
- Transaction: PENDING (never referenced)

RecurringInvoice constants (ACTIVE, ON_HOLD, NONE, COUNT, DATE) are kept
as they are used via hardcoded strings in services, factories, and migrations.

app/Models/Company.php

@@ -21,10 +21,6 @@ class Company extends Model implements HasMedia
         'id',
     ];
 
-    public const COMPANY_LEVEL = 'company_level';
-
-    public const CUSTOMER_LEVEL = 'customer_level';
-
     protected $appends = ['logo', 'logo_path'];
 
     public function getRolesAttribute()

app/Models/Payment.php

@@ -22,16 +22,6 @@ class Payment extends Model implements HasMedia
     use HasFactory;
     use InteractsWithMedia;
 
-    public const PAYMENT_MODE_CHECK = 'CHECK';
-
-    public const PAYMENT_MODE_OTHER = 'OTHER';
-
-    public const PAYMENT_MODE_CASH = 'CASH';
-
-    public const PAYMENT_MODE_CREDIT_CARD = 'CREDIT_CARD';
-
-    public const PAYMENT_MODE_BANK_TRANSFER = 'BANK_TRANSFER';
-
     protected $dates = ['created_at', 'updated_at', 'payment_date'];
 
     protected $guarded = ['id'];

app/Models/Transaction.php

@@ -20,8 +20,6 @@ class Transaction extends Model
         'transaction_date',
     ];
 
-    public const PENDING = 'PENDING';
-
     public const FAILED = 'FAILED';
 
     public const SUCCESS = 'SUCCESS';