Remove export to txt, the .md markdown is really the same

tests/test_db.py

@@ -75,10 +75,6 @@ def test_get_all_entries_and_export(fresh_db, tmp_path):
     fresh_db.export_csv(entries, str(csv_path))
     assert csv_path.exists() and list(csv.reader(open(csv_path)))
 
-    txt_path = tmp_path / "export.txt"
-    fresh_db.export_txt(entries, str(txt_path))
-    assert txt_path.exists() and txt_path.read_text().strip()
-
     md_path = tmp_path / "export.md"
     fresh_db.export_markdown(entries, str(md_path))
     md_text = md_path.read_text()

tests/test_main_window.py

@@ -744,7 +744,6 @@ def test_on_insert_image_calls_editor_insert(
 @pytest.mark.parametrize(
     "filter_label, method",
     [
-        ("Text (*.txt)", "export_txt"),
         ("JSON (*.json)", "export_json"),
         ("CSV (*.csv)", "export_csv"),
         ("HTML (*.html)", "export_html"),
@@ -1172,7 +1171,7 @@ def test_export_cancel_then_empty_filename(
     monkeypatch.setattr(
         mwmod.QFileDialog,
         "getSaveFileName",
-        staticmethod(lambda *a, **k: ("", "Text (*.txt)")),
+        staticmethod(lambda *a, **k: ("", "Markdown (*.md)")),
         raising=False,
     )
     w._export()  # returns early at filename check