Implement version 0.0.2 features

Add product version management:
- ProductVersion model and VersionManager class
- VersionAdminController with meta box on product edit page
- AJAX-based version CRUD (add, delete, toggle status)
- JavaScript for version management UI

Add email notifications:
- LicenseEmailController for order emails
- License keys included in order completed emails
- Support for both HTML and plain text emails

Add REST API rate limiting:
- 30 requests per minute per IP
- Cloudflare and proxy-aware IP detection
- HTTP 429 response with Retry-After header

Other changes:
- Bump version to 0.0.2
- Update CHANGELOG.md
- Add version status styles to admin.css

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

assets/css/admin.css

@@ -89,3 +89,59 @@
 .column-license .dashicons-admin-network {
     color: #2271b1;
 }
+
+/* Version Status Badges */
+.version-status {
+    display: inline-block;
+    padding: 0.2em 0.5em;
+    font-size: 0.85em;
+    font-weight: 500;
+    line-height: 1.2;
+    border-radius: 3px;
+}
+
+.version-status-active {
+    background-color: #d4edda;
+    color: #155724;
+}
+
+.version-status-inactive {
+    background-color: #fff3cd;
+    color: #856404;
+}
+
+/* Version Meta Box */
+.wc-licensed-product-versions .versions-add-form {
+    background: #f9f9f9;
+    padding: 15px;
+    border: 1px solid #e5e5e5;
+    border-radius: 4px;
+    margin-bottom: 20px;
+}
+
+.wc-licensed-product-versions .versions-add-form h4 {
+    margin-top: 0;
+}
+
+.wc-licensed-product-versions .form-table {
+    margin: 0;
+}
+
+.wc-licensed-product-versions .form-table th {
+    padding: 10px 10px 10px 0;
+    width: 120px;
+}
+
+.wc-licensed-product-versions .form-table td {
+    padding: 10px 0;
+}
+
+#versions-table {
+    margin-top: 10px;
+}
+
+#versions-table .no-versions td {
+    text-align: center;
+    font-style: italic;
+    color: #666;
+}