feat: add downloader module with yt-dlp integration

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

tests/test_downloader.py

@@ -0,0 +1,27 @@
+import pytest
+from unittest.mock import Mock, patch
+from src.downloader import download_space
+
+
+def test_download_space_basic(tmp_path):
+    """Test basic download functionality."""
+    space_url = "https://x.com/i/spaces/1ZkKzZWnVRRKv"
+
+    with patch('src.downloader.yt_dlp.YoutubeDL') as mock_ytdl_class:
+        # Mock the YoutubeDL instance
+        mock_ytdl = Mock()
+        mock_ytdl_class.return_value.__enter__.return_value = mock_ytdl
+        mock_ytdl.extract_info.return_value = {'id': '1ZkKzZWnVRRKv'}
+
+        # Call download_space
+        result = download_space(
+            space_url=space_url,
+            output_dir=str(tmp_path),
+            cookies_file=None
+        )
+
+        # Verify YoutubeDL was called
+        mock_ytdl.extract_info.assert_called_once_with(space_url, download=True)
+
+        # Verify result contains expected filename
+        assert "space_1ZkKzZWnVRRKv" in result