Fix team invitation email case sensitivity bug

- Add email normalization to TeamInvitation model using setEmailAttribute()
- Add HasFactory trait to Team model for testing support
- Create TeamFactory for testing
- Add tests to verify email normalization works correctly
- Fixes issue where mixed case emails in invitations would cause lookup failures
- Resolves #6291

The bug occurred because:
1. User model normalizes emails to lowercase
2. TeamInvitation model did not normalize emails
3. When invitation was created with mixed case, it was stored as-is
4. User lookup failed due to case mismatch during invitation acceptance
5. This caused users to not be able to see teams they were invited to

This fix ensures both models normalize emails consistently.

app/Models/Team.php

@@ -10,6 +10,7 @@
 use App\Traits\HasNotificationSettings;
 use App\Traits\HasSafeStringAttribute;
 use Illuminate\Database\Eloquent\Casts\Attribute;
+use Illuminate\Database\Eloquent\Factories\HasFactory;
 use Illuminate\Database\Eloquent\Model;
 use Illuminate\Notifications\Notifiable;
 use OpenApi\Attributes as OA;
@@ -37,7 +38,7 @@
 
 class Team extends Model implements SendsDiscord, SendsEmail, SendsPushover, SendsSlack
 {
-    use HasNotificationSettings, HasSafeStringAttribute, Notifiable;
+    use HasFactory, HasNotificationSettings, HasSafeStringAttribute, Notifiable;
 
     protected $guarded = [];
 

app/Models/TeamInvitation.php

@@ -15,6 +15,14 @@ class TeamInvitation extends Model
         'via',
     ];
 
+    /**
+     * Set the email attribute to lowercase.
+     */
+    public function setEmailAttribute($value)
+    {
+        $this->attributes['email'] = strtolower($value);
+    }
+
     public function team()
     {
         return $this->belongsTo(Team::class);

database/factories/TeamFactory.php

@@ -0,0 +1,40 @@
+<?php
+
+namespace Database\Factories;
+
+use App\Models\Team;
+use Illuminate\Database\Eloquent\Factories\Factory;
+
+/**
+ * @extends \Illuminate\Database\Eloquent\Factories\Factory<\App\Models\Team>
+ */
+class TeamFactory extends Factory
+{
+    protected $model = Team::class;
+
+    /**
+     * Define the model's default state.
+     *
+     * @return array<string, mixed>
+     */
+    public function definition(): array
+    {
+        return [
+            'name' => $this->faker->company() . ' Team',
+            'description' => $this->faker->sentence(),
+            'personal_team' => false,
+            'show_boarding' => false,
+        ];
+    }
+
+    /**
+     * Indicate that the team is a personal team.
+     */
+    public function personal(): static
+    {
+        return $this->state(fn (array $attributes) => [
+            'personal_team' => true,
+            'name' => $this->faker->firstName() . "'s Team",
+        ]);
+    }
+}

tests/Feature/TeamInvitationEmailNormalizationTest.php

@@ -0,0 +1,63 @@
+<?php
+
+namespace Tests\Feature;
+
+use App\Models\Team;
+use App\Models\TeamInvitation;
+use App\Models\User;
+use Illuminate\Foundation\Testing\RefreshDatabase;
+use Tests\TestCase;
+
+class TeamInvitationEmailNormalizationTest extends TestCase
+{
+    use RefreshDatabase;
+
+    public function test_team_invitation_normalizes_email_to_lowercase()
+    {
+        // Create a team
+        $team = Team::factory()->create();
+
+        // Create invitation with mixed case email
+        $invitation = TeamInvitation::create([
+            'team_id' => $team->id,
+            'uuid' => 'test-uuid-123',
+            'email' => 'Test@Example.com', // Mixed case
+            'role' => 'member',
+            'link' => 'https://example.com/invite/test-uuid-123',
+            'via' => 'link'
+        ]);
+
+        // Verify email was normalized to lowercase
+        $this->assertEquals('test@example.com', $invitation->email);
+    }
+
+    public function test_team_invitation_works_with_existing_user_email()
+    {
+        // Create a team
+        $team = Team::factory()->create();
+
+        // Create a user with lowercase email
+        $user = User::factory()->create([
+            'email' => 'test@example.com',
+            'name' => 'Test User'
+        ]);
+
+        // Create invitation with mixed case email
+        $invitation = TeamInvitation::create([
+            'team_id' => $team->id,
+            'uuid' => 'test-uuid-123',
+            'email' => 'Test@Example.com', // Mixed case
+            'role' => 'member',
+            'link' => 'https://example.com/invite/test-uuid-123',
+            'via' => 'link'
+        ]);
+
+        // Verify the invitation email matches the user email (both normalized)
+        $this->assertEquals($user->email, $invitation->email);
+
+        // Verify user lookup works
+        $foundUser = User::whereEmail($invitation->email)->first();
+        $this->assertNotNull($foundUser);
+        $this->assertEquals($user->id, $foundUser->id);
+    }
+}