Fix licenses endpoint 404 error in customer account

- Register licenses query var with WooCommerce via woocommerce_get_query_vars
- Register endpoint in Installer before flushing rewrite rules
- Existing installations need to re-save permalinks

The endpoint was not being recognized because WooCommerce's My Account
requires both add_rewrite_endpoint() and query var registration.

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

CLAUDE.md

@@ -553,3 +553,18 @@ Full API documentation available in `openapi.json` (OpenAPI 3.1 specification).
 - Domain validation with normalization (strips protocol, www prefix)
 - Inline edit UI with save/cancel for license domains
 - Links to full licenses management page for advanced actions
+
+**Bug fix (post v0.0.10):**
+
+- Fixed: Licenses menu item in customer account page resulted in 404 error
+
+**Root cause:**
+
+- WooCommerce My Account endpoints require both `add_rewrite_endpoint()` AND registration with `woocommerce_get_query_vars` filter
+- The endpoint also needs to be registered before rewrite rules are flushed during activation
+
+**Fix:**
+
+- Added `addLicensesQueryVar()` method to register the endpoint query var with WooCommerce
+- Updated Installer to register endpoint before flushing rewrite rules on activation
+- Existing installations may need to visit Settings > Permalinks and click Save to regenerate rewrite rules