system-locked violation types (alpha & terlambat) + proporsional poin alpha per jam

- Migration: add is_system column to violation_types, mark alpha & terlambat
- DestroyType guard: system types cannot be deleted
- UpdateType guard: slug tetap walau nama diubah untuk system types
- UI: delete button hidden, badge lock untuk system types
- Seeder: ViolationTypeDefaultsSeeder untuk fresh deploy
- AttendanceController: lookup by slug (alpha/terlambat) instead of fuzzy match
- Alpha auto-violation: poin proporsional per jam (round((points/10)*count), min 1)
- Terlambat auto-violation: poin fix sesuai jenis (2 poin)
- Also handles both A (alpha) and T (terlambat) statuses for auto-violations

database/migrations/2026_07_22_161010_create_attendances_table.php

@@ -0,0 +1,31 @@
+<?php
+
+use Illuminate\Database\Migrations\Migration;
+use Illuminate\Database\Schema\Blueprint;
+use Illuminate\Support\Facades\Schema;
+
+return new class extends Migration
+{
+    public function up(): void
+    {
+        Schema::create('attendances', function (Blueprint $table) {
+            $table->id();
+            $table->foreignId('student_id')->constrained()->cascadeOnDelete();
+            $table->date('date');
+            $table->unsignedTinyInteger('lesson_hour')->comment('Jam ke- 1 s.d 10');
+            $table->string('status', 20)->default('hadir')->comment('hadir|sakit|izin|alpha|terlambat');
+            $table->text('notes')->nullable();
+            $table->foreignId('recorded_by')->nullable()->constrained('users')->nullOnDelete();
+            $table->timestamps();
+
+            $table->unique(['student_id', 'date', 'lesson_hour'], 'attendance_unique');
+            $table->index('date');
+            $table->index('status');
+        });
+    }
+
+    public function down(): void
+    {
+        Schema::dropIfExists('attendances');
+    }
+};