fix: implement password change for shop customers

The password change form on the profile page (``Mes coordonnées``)
was scaffolded but never wired to any backend logic. The fields
``current-password``, ``new-password`` and ``new-password_confirmation``
were silently ignored by ``Customers::storeFull()``.

- Add ``handlePasswordChange()`` in ``CustomerController`` that
  validates current password, confirmation match, and 8-char minimum
  before hashing and saving.
- Remove ``required`` attribute from password fields so the form can
  submit for profile-only updates without filling password fields.
- Strip password fields from request data before passing to
  ``storeFull()`` to avoid Eloquent mass-assignment noise.

resources/views/Shop/auth/passwords/password_confirmation.blade.php

@@ -13,7 +13,7 @@
     <label for="new-password" class="col-md-6 control-label text-right">Nouveau mot de passe</label>
 
     <div class="col-md-6">
-        <input id="new-password" type="password" class="form-control" name="new-password" required>
+        <input id="new-password" type="password" class="form-control" name="new-password">
     </div>
 </div>
 
@@ -21,6 +21,6 @@
     <label for="new-password-confirm" class="col-md-6 control-label text-right">Confirmez votre mot de passe</label>
 
     <div class="col-md-6">
-        <input id="new-password-confirm" type="password" class="form-control" name="new-password_confirmation" required>
+        <input id="new-password-confirm" type="password" class="form-control" name="new-password_confirmation">
     </div>
 </div>