Implement version 0.0.1 - Licensed Product type for WooCommerce

Add complete plugin infrastructure for selling software with license keys:

- New "Licensed Product" WooCommerce product type
- License key generation (XXXX-XXXX-XXXX-XXXX format) on order completion
- Domain-based license validation system
- REST API endpoints (validate, status, activate, deactivate)
- Customer My Account "Licenses" page
- Admin license management under WooCommerce > Licenses
- Checkout domain field for licensed products
- Custom database tables for licenses and product versions
- Twig template engine integration
- Full i18n support with German (de_CH) translation

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

assets/css/admin.css

@@ -0,0 +1,91 @@
+/**
+ * WC Licensed Product - Admin Styles
+ *
+ * @package Jeremias\WcLicensedProduct
+ */
+
+/* License Status Badges */
+.license-status {
+    display: inline-block;
+    padding: 0.2em 0.5em;
+    font-size: 0.85em;
+    font-weight: 500;
+    line-height: 1.2;
+    border-radius: 3px;
+}
+
+.license-status-active {
+    background-color: #d4edda;
+    color: #155724;
+}
+
+.license-status-inactive {
+    background-color: #fff3cd;
+    color: #856404;
+}
+
+.license-status-expired {
+    background-color: #f8d7da;
+    color: #721c24;
+}
+
+.license-status-revoked {
+    background-color: #d6d8db;
+    color: #383d41;
+}
+
+/* License Table */
+.wp-list-table code {
+    font-family: monospace;
+    background-color: #f0f0f0;
+    padding: 0.15em 0.4em;
+    border-radius: 3px;
+    font-size: 0.9em;
+}
+
+/* License Product Tab */
+#woocommerce-product-data .show_if_licensed {
+    display: block !important;
+}
+
+#woocommerce-product-data .hide_if_licensed {
+    display: none !important;
+}
+
+/* Action Buttons */
+.wp-list-table .button-link-delete {
+    color: #a00;
+}
+
+.wp-list-table .button-link-delete:hover {
+    color: #dc3232;
+}
+
+/* Pagination */
+.tablenav-pages .pagination-links {
+    display: flex;
+    align-items: center;
+    gap: 0.5em;
+}
+
+.tablenav-pages .paging-input {
+    margin: 0 0.5em;
+}
+
+/* Orders Column */
+.column-license {
+    width: 15%;
+}
+
+.column-license .dashicons {
+    vertical-align: middle;
+    margin-right: 0.3em;
+}
+
+.column-license .dashicons-warning {
+    color: #dba617;
+}
+
+.column-license .dashicons-admin-network {
+    color: #2271b1;
+}