feat: add stream-copy exports

tests/test_ui_structure.py

@@ -54,6 +54,27 @@ def test_workers_spinbox_in_export_tab(win):
     assert win._spn_workers in win._tab_export.findChildren(QSpinBox)
 
 
+def test_clip_duration_allows_long_exports(win):
+    assert win._spn_clip_dur.maximum() >= 86400.0
+
+
+def test_stream_copy_mode_disables_transforms(win):
+    win._file_path = "/x/source.mkv"
+    win._cmb_format.setCurrentText("WebP sequence")
+    win._chk_stream_copy.setChecked(True)
+    try:
+        assert win._stream_copy_active()
+        assert win._source_container_extension() == ".mkv"
+        assert win._cmb_format.currentText() == "MP4"
+        assert win._cmb_format.isHidden()
+        assert not win._chk_hw.isEnabled()
+        assert not win._spn_resize.isEnabled()
+        assert not win._cmb_portrait.isEnabled()
+        assert not win._chk_track.isEnabled()
+    finally:
+        win._chk_stream_copy.setChecked(False)
+
+
 def test_scan_button_in_audio_tab(win):
     from PyQt6.QtWidgets import QPushButton
     assert win._btn_scan in win._tab_audio.findChildren(QPushButton)