feat(launcher): add portable windows launcher (#976)

* feat(windows): add standalone portable executable, splash screen, and system tray

* test: fix test_get_wsl_windows_user_profile_falls_back_to_users_dir on Windows

* Refactor launcher: isolate desktop logic into launcher.py, clean app.py/requirements, update build scripts, and add tests

* chore: clean launcher test whitespace

---------

Co-authored-by: Alexandre Teixeira <alexandremagteixeira@gmail.com>

tests/test_launcher.py

@@ -0,0 +1,62 @@
+# tests/test_launcher.py
+import sys
+import os
+from unittest import mock
+import pytest
+
+from launcher import NullWriter, create_tray_image, on_open_browser, on_exit, open_browser
+
+
+def test_null_writer():
+    writer = NullWriter()
+    # writing and flushing should not raise any exceptions
+    writer.write("hello")
+    writer.flush()
+    assert writer.isatty() is False
+
+
+def test_create_tray_image():
+    try:
+        from PIL import Image
+        img = create_tray_image()
+        assert isinstance(img, Image.Image)
+        assert img.size == (64, 64)
+    except ImportError:
+        pytest.skip("Pillow/PIL not installed in test environment")
+
+
+def test_on_open_browser():
+    with mock.patch("webbrowser.open") as mock_open:
+        icon_mock = mock.Mock()
+        item_mock = mock.Mock()
+        url = "http://127.0.0.1:7000"
+        on_open_browser(icon_mock, item_mock, url)
+        mock_open.assert_called_once_with(url)
+
+
+def test_on_exit():
+    with mock.patch("os._exit") as mock_exit:
+        icon_mock = mock.Mock()
+        item_mock = mock.Mock()
+        on_exit(icon_mock, item_mock)
+        icon_mock.stop.assert_called_once()
+        mock_exit.assert_called_once_with(0)
+
+
+def test_open_browser():
+    with mock.patch("webbrowser.open") as mock_open, \
+         mock.patch("time.sleep") as mock_sleep:
+
+        # Test when splash_root is None
+        with mock.patch("launcher.splash_root", None):
+            open_browser("http://127.0.0.1:7000")
+            mock_open.assert_called_once_with("http://127.0.0.1:7000")
+            mock_sleep.assert_called_once_with(3.5)
+
+    with mock.patch("webbrowser.open") as mock_open, \
+         mock.patch("time.sleep") as mock_sleep:
+        # Test when splash_root is present and gets destroyed
+        mock_splash = mock.Mock()
+        with mock.patch("launcher.splash_root", mock_splash):
+            open_browser("http://127.0.0.1:7000")
+            mock_splash.after.assert_called_once()