Fixed relative custom URL breaks when Magento store code is included in URLs

[Kashyap1999]

Description

When adding a Custom URL menu item, internal paths like /contact or contact didn’t include the store’s base URL when “Add Store Code to URLs” was enabled.

This caused links to break on non-default store views — for example, /contact rendered as /contact instead of /storeB/contact.

Fix:

• Added logic to resolve internal URLs with the correct store base URL (including store code).
• Updated templates to use the resolved URL method.
• External URLs (e.g., https://google.com) remain unaffected.

Fixes #376.