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/ManagesShippingLabels.php

@@ -0,0 +1,85 @@
+<?php
+
+namespace Anikeen\Id\Concerns;
+
+use Anikeen\Id\Result;
+use Throwable;
+
+/**
+ * Shipping labels (Deutsche Post Internetmarke). Trusted apps only, sent with the app's token.
+ */
+trait ManagesShippingLabels
+{
+    /**
+     * Latest shipping labels (100 per page).
+     *
+     * @throws Throwable
+     */
+    public function shippingLabels(array $parameters = []): Result
+    {
+        return $this->asApp()->request('GET', 'v1/admin/shipping-labels', null, $parameters);
+    }
+
+    /**
+     * @throws Throwable
+     */
+    public function shippingLabel(string $id): Result
+    {
+        return $this->asApp()->request('GET', sprintf('v1/admin/shipping-labels/%s', $id));
+    }
+
+    /**
+     * The label as PDF (binary string), null if there is none.
+     *
+     * @throws Throwable
+     */
+    public function shippingLabelPdf(string $id): ?string
+    {
+        $result = $this->asApp()->request('GET', sprintf('v1/admin/shipping-labels/%s/pdf', $id));
+
+        return $result->success() ? (string) $result->response()->getBody() : null;
+    }
+
+    /**
+     * Buy a shipping label; the postage is billed to the given user.
+     *
+     * @param array{
+     *     box: array,
+     *     weight: int,
+     *     address: array,
+     *     billed_user_id: string,
+     *     test?: bool
+     * } $attributes
+     *   - box:            barcode, id, common_name or size of the box
+     *   - weight:         in grams
+     *   - address:        recipient address
+     *   - billed_user_id: Anikeen ID of the user who pays the postage
+     *   - test:           validate only, no real label is bought
+     * @throws Throwable
+     */
+    public function issueShippingLabel(array $attributes): Result
+    {
+        return $this->asApp()->request('POST', 'v1/admin/shipping-labels/issue', $attributes);
+    }
+
+    /**
+     * Mark the label with the scanned matrix code as shipped.
+     *
+     * @param list<string> $hex Hex bytes of the scanned Internetmarke matrix code
+     * @throws Throwable
+     */
+    public function shipShippingLabel(array $hex): Result
+    {
+        return $this->asApp()->request('POST', 'v1/admin/shipping-labels/ship', ['hex' => $hex]);
+    }
+
+    /**
+     * Prices of the available franking types.
+     *
+     * @throws Throwable
+     */
+    public function shippingPriceList(): Result
+    {
+        return $this->asApp()->request('GET', 'v1/admin/shipping-labels/price-list');
+    }
+}