feat: penanganan pelanggaran (handling system)

- Migration: handling_status, handled_at, handled_by ke violations
- Migration: tabel violation_handlings, handling_participants
- Model: ViolationHandling, HandlingParticipant + relasi
- Routes: storeHandling, resolveHandling, destroyHandling, calendar data
- ViolationController: CRUD penanganan + filter status handling
- DashboardController: data handling stats + calendar endpoint
- Dashboard view: kalender pelanggaran interaktif (Alpine.js)
- Violations index: filter status penanganan + kolom status
- Violations show: stat card penanganan + timeline + modal tambah
- Menambahkan handling_status filter di index

app/Models/HandlingParticipant.php

@@ -0,0 +1,21 @@
+<?php
+
+namespace App\Models;
+
+use Illuminate\Database\Eloquent\Model;
+use Illuminate\Database\Eloquent\Relations\BelongsTo;
+
+class HandlingParticipant extends Model
+{
+    protected $fillable = ['handling_id', 'user_id', 'role'];
+
+    public function handling(): BelongsTo
+    {
+        return $this->belongsTo(ViolationHandling::class, 'handling_id');
+    }
+
+    public function user(): BelongsTo
+    {
+        return $this->belongsTo(User::class);
+    }
+}