chore: bump version 02.30.00 → 02.31.00, cleanup legacy jmiller user

- Version bump across all manifests and docs
- Auto-cleanup of legacy master users no longer in MASTER_KEYS
- Updated CHANGELOG with all 02.31.00 changes

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

src/script.php

@@ -230,7 +230,7 @@ class Pkg_MokowaasInstallerScript
 	 *
 	 * @return  void
 	 *
-	 * @since   02.30.00
+	 * @since   02.31.00
 	 */
 	private function cleanupStaleUpdateSites(): void
 	{