completed story 1.1 with QA tests and fixes

app/Models/TimelineUpdate.php

@@ -0,0 +1,34 @@
+<?php
+
+namespace App\Models;
+
+use Illuminate\Database\Eloquent\Factories\HasFactory;
+use Illuminate\Database\Eloquent\Model;
+use Illuminate\Database\Eloquent\Relations\BelongsTo;
+
+class TimelineUpdate extends Model
+{
+    use HasFactory;
+
+    protected $fillable = [
+        'timeline_id',
+        'admin_id',
+        'update_text',
+    ];
+
+    /**
+     * Get the timeline that owns the update.
+     */
+    public function timeline(): BelongsTo
+    {
+        return $this->belongsTo(Timeline::class);
+    }
+
+    /**
+     * Get the admin that created the update.
+     */
+    public function admin(): BelongsTo
+    {
+        return $this->belongsTo(User::class, 'admin_id');
+    }
+}