feat: resolve mokocassiopeia download URL from updates.xml

Instead of hardcoding the zip URL, fetches MokoCassiopeia's updates.xml
from the repo main branch and parses the downloadurl. This way the
download location is controlled by the MokoCassiopeia repo.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/script.php

@@ -251,9 +251,22 @@ class plgSystemMokoWaaSInstallerScript implements InstallerScriptInterface
 			return;
 		}
 
-		// Template not installed — try to install from GitHub
-		$zipUrl  = 'https://github.com/mokoconsulting-tech/MokoCassiopeia'
-			. '/releases/latest/download/MokoCassiopeia.zip';
+		// Template not installed — get download URL from updates.xml
+		$updatesUrl = 'https://raw.githubusercontent.com'
+			. '/mokoconsulting-tech/MokoCassiopeia/main/updates.xml';
+
+		$zipUrl = $this->getDownloadUrlFromUpdates($updatesUrl);
+
+		if (empty($zipUrl))
+		{
+			Factory::getApplication()->enqueueMessage(
+				'MokoCassiopeia: could not resolve download URL.',
+				'warning'
+			);
+
+			return;
+		}
+
 		$tmpFile = JPATH_ROOT . '/tmp/mokocassiopeia.zip';
 		$tmpDir  = JPATH_ROOT . '/tmp/mokocassiopeia';
 
@@ -366,6 +379,41 @@ class plgSystemMokoWaaSInstallerScript implements InstallerScriptInterface
 		$db->execute();
 	}
 
+	/**
+	 * Parse an updates.xml and return the download URL.
+	 *
+	 * @param   string  $updatesUrl  URL to the updates.xml file
+	 *
+	 * @return  string|null  Download URL or null on failure
+	 *
+	 * @since   02.01.01
+	 */
+	private function getDownloadUrlFromUpdates($updatesUrl)
+	{
+		try
+		{
+			$xml = @file_get_contents($updatesUrl);
+
+			if ($xml === false)
+			{
+				return null;
+			}
+
+			$updates = new \SimpleXMLElement($xml);
+
+			if (isset($updates->update->downloads->downloadurl))
+			{
+				return (string) $updates->update->downloads->downloadurl;
+			}
+		}
+		catch (\Exception $e)
+		{
+			return null;
+		}
+
+		return null;
+	}
+
 	private const BLOCK_START = '; ===== BEGIN MokoWaaS Overrides (do not edit this block) =====';
 
 	/** Sentinel comment that marks the end of MokoWaaS overrides inside a Joomla override file. */