File drops from the file manager insert at the drop position

The table already computed and emitted the drop row for external URL
drops, but PlaylistView._on_files_dropped threw it away, so imported
files always appended. Thread it through: playlist_view.files_dropped
gains a row slot (None = append), MainWindow.import_files and
file_importer.import_paths take an optional position and hand it to
add_tracks_to_playlist, which already supported positional insert.
Files already in the library dedup to the existing track and insert at
the drop position without duplicating the library entry.

lintunes/gui/main_window.py

@@ -314,16 +314,18 @@ class MainWindow(QMainWindow):
         if paths:
             self.import_files([Path(p) for p in paths])
 
-    def import_files(self, paths, playlist_pid: str = ""):
+    def import_files(self, paths, playlist_pid: str = "",
+                     position: int | None = None):
         self.statusBar().showMessage(f"Importing {len(paths)} item(s)…")
         imported = file_importer.import_paths(
-            paths, self._music_import_dir(), self._manager, playlist_pid)
+            paths, self._music_import_dir(), self._manager, playlist_pid,
+            position)
         self.statusBar().showMessage(f"Imported {len(imported)} track(s)", 5000)
         if imported:
             self._library_view.reload()
 
-    def _import_files_to_playlist(self, paths, pid):
-        self.import_files([Path(p) for p in paths], pid)
+    def _import_files_to_playlist(self, paths, pid, position=None):
+        self.import_files([Path(p) for p in paths], pid, position)
 
     # ---- album art download ----
 

lintunes/gui/playlist_view.py

@@ -9,7 +9,7 @@ from lintunes.gui.playlist_ops import add_tracks_with_dup_check
 class PlaylistView(TableSettingsMixin, QWidget):
     play_requested = pyqtSignal(list, int)
     info_requested = pyqtSignal(list)
-    files_dropped = pyqtSignal(list, str)  # paths, playlist pid
+    files_dropped = pyqtSignal(list, str, object)  # paths, pid, row or None
     show_in_playlist_requested = pyqtSignal(int, str)  # track_id, playlist pid
 
     def __init__(self, manager, parent=None):
@@ -124,7 +124,8 @@ class PlaylistView(TableSettingsMixin, QWidget):
 
     def _on_files_dropped(self, paths, drop_row):
         if self._editable():
-            self.files_dropped.emit(paths, self._playlist.persistent_id)
+            self.files_dropped.emit(
+                paths, self._playlist.persistent_id, drop_row)
 
     def _on_remove(self, rows):
         if self._editable():