feat: security advisory aggregator, manifest API rewrite, namespace rename (#150, #283)

- Add `security:advisories` command — cross-repo CVE scanner via composer audit
  with checkpoint resumability, severity filtering, and auto-issue creation
- Rewrite `manifest:read` to use Gitea manifest API as primary source with
  auto-detection fallback from source tree (no more manifest.xml dependency)
- Rename MokoStandards namespace → MokoCli across all files
- Rename MokoEnterprise namespace → MokoCli across all files
- Rename MokoStandardsParser class → ManifestParser
- Fix composer.json autoload paths: src/ → source/

plugin_validate.php

@@ -19,9 +19,9 @@ declare(strict_types=1);
 // Autoload dependencies
 require_once __DIR__ . '/../vendor/autoload.php';
 
-use MokoEnterprise\PluginFactory;
-use MokoEnterprise\AuditLogger;
-use MokoEnterprise\MetricsCollector;
+use MokoCli\PluginFactory;
+use MokoCli\AuditLogger;
+use MokoCli\MetricsCollector;
 
 /**
  * Display usage information