Bring the package up to date with the Anikeen ID API

Fixed (called endpoints that don't exist):
- charge(): POST v1/billing/charge (Stripe options aren't passed through anymore)
- Invoice::getInvoiceTemporaryUrl(): GET instead of a non-existent PUT
- OrderItems::create(): POST v1/orders/{order}/items
- createUser() / isEmailExisting(): admin endpoints with the app token
- sshKeysByUserId(): app endpoint; no longer returns the first user's keys for every user
- createOrderPreview(): country_iso goes into billing_address as the API expects
- public endpoints (products, order preview) work without a token
- SshKeys::find() results can be deleted

Added:
- Billable: sshKeys() (create, update, delete), billingOverview(), PaymentMethod::delete()
- AnikeenId: products(), boxes(), shipping labels (list, show, pdf, issue, ship, price list),
  createOrderForUser(), createTransactionForUser(), findOrCreateSocialiteUser()

Requirements: PHP 8.2+, Laravel 11-13 (Laravel 10 and PHP 8.1 are end of life).
Docs generator handles union types; README regenerated.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

src/Id/AnikeenId.php

@@ -3,8 +3,11 @@
 namespace Anikeen\Id;
 
 use Anikeen\Id\Concerns\ManagesPricing;
+use Anikeen\Id\Concerns\ManagesProducts;
+use Anikeen\Id\Concerns\ManagesShippingLabels;
 use Anikeen\Id\Concerns\ManagesSocialiteUsers;
 use Anikeen\Id\Concerns\ManagesSshKeys;
+use Anikeen\Id\Concerns\ManagesUserBilling;
 use Anikeen\Id\Concerns\ManagesUsers;
 use Anikeen\Id\Exceptions\RequestRequiresAuthenticationException;
 use Anikeen\Id\Exceptions\RequestRequiresClientIdException;
@@ -21,6 +24,9 @@ class AnikeenId
 {
     use OauthTrait;
     use ManagesPricing;
+    use ManagesProducts;
+    use ManagesShippingLabels;
+    use ManagesUserBilling;
     use ManagesSocialiteUsers;
     use ManagesSshKeys;
     use ManagesUsers;
@@ -398,7 +404,8 @@ class AnikeenId
             'Client-ID' => $this->getClientId(),
             'Accept' => 'application/json',
         ];
-        if ($bearerToken = $useClientSecret ? $this->getClientSecret() : $this->getToken()) {
+        // public endpoints (products, order preview, …) work without a token
+        if ($bearerToken = $useClientSecret ? $this->getClientSecret() : $this->token) {
             $headers['Authorization'] = 'Bearer ' . $bearerToken;
         }
         if ($json) {