Improve URL detection logic and add test coverage for domain-only inputs

Co-authored-by: swissspidy <841956+swissspidy@users.noreply.github.com>

Author: Copilot

features/site.feature

@@ -843,3 +843,51 @@ Feature: Manage sites in a multisite installation
       Error: Could not find site with URL: http://example.com/nonexistent/
       """
     And the return code should be 1
+
+  Scenario: Get site by domain without scheme
+    Given a WP multisite subdirectory install
+
+    When I run `wp site create --slug=noscheme --porcelain`
+    Then STDOUT should be a number
+    And save STDOUT as {SITE_ID}
+
+    When I run `wp site get example.com/noscheme/ --field=blog_id`
+    Then STDOUT should be:
+      """
+      {SITE_ID}
+      """
+
+  Scenario: Get site by simple domain path
+    Given a WP multisite subdirectory install
+
+    When I run `wp site create --slug=simplepath --porcelain`
+    Then STDOUT should be a number
+    And save STDOUT as {SITE_ID}
+
+    When I run `wp site get example.com/simplepath --field=blog_id`
+    Then STDOUT should be:
+      """
+      {SITE_ID}
+      """
+
+  Scenario: Get site by subdomain without scheme
+    Given a WP multisite subdomain install
+
+    When I run `wp site create --slug=subdomain --porcelain`
+    Then STDOUT should be a number
+    And save STDOUT as {SITE_ID}
+
+    When I run `wp site get subdomain.example.com --field=blog_id`
+    Then STDOUT should be:
+      """
+      {SITE_ID}
+      """
+
+  Scenario: Get main site by domain
+    Given a WP multisite install
+
+    When I run `wp site get example.com --field=blog_id`
+    Then STDOUT should be:
+      """
+      1
+      """

src/Site_Command.php

@@ -460,12 +460,12 @@ public function get( $args, $assoc_args ) {
 		$site_arg = $args[0];
 		$site     = null;
 
-		// Check if the argument is a URL (contains :// or starts with www.)
-		if ( false !== strpos( $site_arg, '://' ) || 0 === strpos( $site_arg, 'www.' ) ) {
-			// Normalize scheme-less URLs starting with www. for proper parsing.
+		// Check if the argument is a URL or a domain (non-numeric)
+		if ( ! is_numeric( $site_arg ) ) {
+			// Normalize URLs without a scheme for proper parsing.
 			$url_to_parse = $site_arg;
-			if ( 0 === strpos( $site_arg, 'www.' ) && false === strpos( $site_arg, '://' ) ) {
-				$url_to_parse = 'http://' . $site_arg;
+			if ( false === strpos( $url_to_parse, '://' ) ) {
+				$url_to_parse = 'http://' . $url_to_parse;
 			}
 
 			// Parse the URL to get domain and path