Refactor ShiftForm to streamline field definitions and implement unique code generation for shifts based on their names. Update ShiftFactory to utilize the new code generation method.

tests/Feature/Models/ShiftTest.php

@@ -0,0 +1,44 @@
+<?php
+
+declare(strict_types=1);
+
+use App\Models\Shift;
+
+it('generates an uppercase slug code from name', function (): void {
+    expect(Shift::generateUniqueCodeFromName('Morning Shift'))
+        ->toBe('MORNING-SHIFT');
+});
+
+it('generates code on save when code is blank', function (): void {
+    $shift = Shift::factory()->create([
+        'name' => 'Morning Shift',
+        'code' => '',
+    ]);
+
+    expect($shift->code)->toBe('MORNING-SHIFT');
+});
+
+it('does not overwrite an existing code on update', function (): void {
+    $shift = Shift::factory()->create([
+        'name' => 'Morning Shift',
+        'code' => 'MS',
+    ]);
+
+    $shift->update(['name' => 'Early Shift']);
+
+    expect($shift->fresh()->code)->toBe('MS');
+});
+
+it('appends a suffix when the generated code already exists', function (): void {
+    Shift::factory()->create([
+        'name' => 'Morning Team',
+        'code' => 'MORNING',
+    ]);
+
+    $shift = Shift::factory()->create([
+        'name' => 'Morning',
+        'code' => '',
+    ]);
+
+    expect($shift->code)->toBe('MORNING-1');
+});