Make the sync result look right with any number of columns

- Visible columns share the width equally, whether one or five are shown
- Long soundtrack names and errors wrap inside their column instead of
  widening the window, which pushed the title and Restart button out of
  view and cut off text
- Separators only go between columns; the extra one before the first
  column is gone
- Wider, centred panel with inner margins, and spacing above the
  Restart button
- The Re-added header no longer reads ReAdded

tests/integration/test_sync_window.gd

@@ -153,3 +153,48 @@ func test_errors_section_has_errors_header() -> void:
     _finish_sync(result)
 
     assert_str((_node("CatchedErrorsVBox").get_child(0) as Label).text).is_equal("Errors")
+
+
+func test_long_names_wrap_instead_of_widening_the_window() -> void:
+    _runner.invoke("start_sync")
+    var long_name: String = "The Legend of Zelda: Breath of the Wild Original Soundtrack"
+    var result: Dictionary = _empty_result()
+    result.soundtracks_added = [long_name]
+    result.soundtracks_re_added = [long_name]
+    result.soundtracks_changed_content = [long_name]
+    result.soundtracks_removed = [long_name]
+    result.soundtracks_changed_title = {long_name: long_name}
+    result.catched_errors = [long_name + " could not be read"]
+
+    _finish_sync(result)
+    await _runner.simulate_frames(2)
+
+    # The minimum width is what the content needs; wider than the panel it would stick out
+    var panel_width: float = (_window.get_node("SyncPanel") as Control).size.x
+    assert_float(_node("SyncHBoxContainer").get_combined_minimum_size().x) \
+            .is_less(panel_width)
+    assert_float(_node("CatchedErrorsVBox").get_combined_minimum_size().x) \
+            .is_less(panel_width)
+
+
+func test_visible_columns_share_the_width_equally() -> void:
+    _runner.invoke("start_sync")
+    var result: Dictionary = _empty_result()
+    result.soundtracks_added = ["Chrono Cross", "Xenoblade Chronicles X Original Soundtrack"]
+    result.soundtracks_removed = ["Bad Rip"]
+
+    _finish_sync(result)
+    await _runner.simulate_frames(2)
+
+    assert_float(_node("SoundtracksAddedVBox").size.x).is_equal_approx(
+            _node("SoundtracksRemovedVBox").size.x, 1.0)
+
+
+func test_column_headers() -> void:
+    _runner.invoke("start_sync")
+    var result: Dictionary = _empty_result()
+    result.soundtracks_re_added = ["Super Metroid"]
+
+    _finish_sync(result)
+
+    assert_str((_node("SoundtracksReAddedVBox").get_child(0) as Label).text).is_equal("Re-added")