fix(dropdown): improve external link detection

[msmps]

Description

• Fix external link detection in Dropdown to also check for http:// and // (protocol-relative URLs)
• Previously only https:// links opened in a new tab

Problem

The DropdownMenuItem component's external link detection only checked for https://:

const isExternal = href.startsWith("https://");

This meant http:// links and protocol-relative URLs (//example.com) were incorrectly treated as internal links and routed through LinkComponent instead of opening in a new tab.

Solution

Use a regex to match all external URL patterns:

const isExternal = /^(https?:)?\/\//.test(href);

Pattern	Matches
https://example.com	External
http://example.com	External
//example.com	External
/dashboard	Internal