Add comprehensive test coverage and update notes

tests/Unit/UpdateUserPasswordTest.php

@@ -0,0 +1,44 @@
+<?php
+
+use App\Actions\Fortify\UpdateUserPassword;
+use App\Models\User;
+use Illuminate\Support\Facades\Hash;
+use Illuminate\Validation\ValidationException;
+
+it('updates password when current password matches', function (): void {
+    $user = User::factory()->create([
+        'password' => Hash::make('OldPass123!'),
+    ]);
+    $this->actingAs($user);
+
+    $action = new UpdateUserPassword();
+
+    $action->update($user, [
+        'current_password' => 'OldPass123!',
+        'password' => 'NewPass123!',
+        'password_confirmation' => 'NewPass123!',
+    ]);
+
+    $user->refresh();
+    expect(Hash::check('NewPass123!', $user->password))->toBeTrue();
+});
+
+it('rejects wrong current password', function (): void {
+    $user = User::factory()->create([
+        'password' => Hash::make('OldPass123!'),
+    ]);
+    $this->actingAs($user);
+
+    $action = new UpdateUserPassword();
+
+    try {
+        $action->update($user, [
+            'current_password' => 'WrongPass',
+            'password' => 'NewPass123!',
+            'password_confirmation' => 'NewPass123!',
+        ]);
+        $this->fail('Expected ValidationException not thrown.');
+    } catch (ValidationException $e) {
+        expect($e->errors())->toHaveKey('current_password');
+    }
+});