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/Concerns/ManagesProducts.php

@@ -0,0 +1,29 @@
+<?php
+
+namespace Anikeen\Id\Concerns;
+
+use Anikeen\Id\Result;
+use Throwable;
+
+trait ManagesProducts
+{
+    /**
+     * Public product catalogue.
+     *
+     * @throws Throwable
+     */
+    public function products(): Result
+    {
+        return $this->request('GET', 'v1/products');
+    }
+
+    /**
+     * Shipping boxes (for shipping labels).
+     *
+     * @throws Throwable
+     */
+    public function boxes(): Result
+    {
+        return $this->request('GET', 'v1/boxes');
+    }
+}