Initial commit: Aplikasi Ketertiban Siswa

- Fitur: input pelanggaran, sistem poin, surat peringatan otomatis, SP progress
- Realtime notifikasi via Laravel Reverb + Echo
- Dashboard statistik, manajemen user, manajemen master data
- Login 2 kolom premium, user dropdown, pengaturan akun
- Tema biru kalem, logo sekolah dinamis, sidebar brand dinamis
- Sinkronisasi siswa dari Database Kesiswaan via API

app/Models/SpLetter.php

@@ -0,0 +1,40 @@
+<?php
+
+namespace App\Models;
+
+use Illuminate\Database\Eloquent\Model;
+
+class SpLetter extends Model
+{
+    protected $fillable = [
+        'student_id', 'sp_threshold_id', 'generated_by',
+        'letter_number', 'title', 'body', 'total_points_at_time',
+        'violations_included', 'status', 'file_path',
+        'printed_at', 'delivered_at',
+    ];
+
+    protected function casts(): array
+    {
+        return [
+            'total_points_at_time' => 'integer',
+            'violations_included' => 'json',
+            'printed_at' => 'datetime',
+            'delivered_at' => 'datetime',
+        ];
+    }
+
+    public function student()
+    {
+        return $this->belongsTo(Student::class);
+    }
+
+    public function spThreshold()
+    {
+        return $this->belongsTo(SpThreshold::class, 'sp_threshold_id');
+    }
+
+    public function generator()
+    {
+        return $this->belongsTo(User::class, 'generated_by');
+    }
+}