fix(batch): resolve pandoc path handling and include-subfolders option

- Normalize pandoc command parsing with path.basename() to support bundled binary paths
- Use bundled pandoc binary in convertWithPandoc instead of relying on PATH
- Forward includeSubfolders checkbox state from renderer to main process
- Add pandoc availability check before batch conversion
- Re-enable Start button when batch conversion completes
- Clean up obsolete dist build artifact causing test snapshot warning
- Bump version to 4.4.4

tests/bundled-tools.test.js

@@ -0,0 +1,28 @@
+/**
+ * Tests for bundled external tools
+ */
+
+const fs = require('fs');
+const path = require('path');
+
+describe('Bundled Pandoc binary', () => {
+  const rootDir = path.resolve(__dirname, '..');
+  const platform = process.platform;
+  const binaryPath = path.join(rootDir, 'bin', platform, 'pandoc');
+  const windowsBinaryPath = path.join(rootDir, 'bin', platform, 'pandoc.exe');
+
+  test('Pandoc binary exists for current platform', () => {
+    const exists = fs.existsSync(binaryPath) || fs.existsSync(windowsBinaryPath);
+    expect(exists).toBe(true);
+  });
+
+  test('Pandoc binary is executable', () => {
+    if (platform === 'win32') {
+      expect(fs.existsSync(windowsBinaryPath)).toBe(true);
+    } else {
+      expect(fs.existsSync(binaryPath)).toBe(true);
+      const stats = fs.statSync(binaryPath);
+      expect(stats.mode & 0o111).toBeGreaterThan(0);
+    }
+  });
+});