fix: use PaddedCell as plugin id to match directory name

- Change plugin id from 'padded-cell' to 'PaddedCell'
- Update manifest and install script
- OpenClaw infers plugin id from directory name

install.mjs

@@ -22,7 +22,7 @@ const __filename = fileURLToPath(import.meta.url);
 const __dirname = resolve(dirname(__filename));
 
 // Plugin configuration
-const PLUGIN_NAME = 'padded-cell';
+const PLUGIN_NAME = 'PaddedCell';
 
 // Parse arguments
 const args = process.argv.slice(2);