Fix renamePortable script to match electron-builder output name

The script looked for Vapourkit-${version}-win.7z but electron-builder
produces Vapourkit-${version}-vapourkit-gui.7z, so the rename was
silently skipped on every build since the script was introduced.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: Kim2091

scripts/renamePortable.ts

@@ -8,7 +8,7 @@ import { join } from 'path';
 import { version } from '../package.json';
 
 const releaseDir = join(__dirname, '..', 'release');
-const oldName = `Vapourkit-${version}-win.7z`;
+const oldName = `Vapourkit-${version}-vapourkit-gui.7z`;
 const newName = `Vapourkit-${version}-PORTABLE.7z`;
 
 const oldPath = join(releaseDir, oldName);