feat: Initial commit for Saqel Platform architecture, backend, Docker, and documentation

backend/app/Models/ConceptMastery.php

@@ -0,0 +1,29 @@
+<?php
+
+namespace App\Models;
+
+use Illuminate\Database\Eloquent\Model;
+use Illuminate\Database\Eloquent\Relations\BelongsTo;
+
+class ConceptMastery extends Model
+{
+    protected $table = 'concept_mastery';
+
+    protected $fillable = [
+        'user_id',
+        'concept_id',
+        'correct_count',
+        'wrong_count',
+        'mastery_score',
+    ];
+
+    public function concept(): BelongsTo
+    {
+        return $this->belongsTo(Concept::class);
+    }
+
+    public function user(): BelongsTo
+    {
+        return $this->belongsTo(User::class);
+    }
+}