refactor: move folder assurance after migrations

The folder assurance has been present since the very first SQL commit e5e7b8afc6,
and thus only has an effect when the library is moved, meaning that is semantically not part of the migrations.

src/tagstudio/core/library/alchemy/library.py

@@ -469,7 +469,7 @@ class Library:
             session.add(Version(key=DB_VERSION_CURRENT_KEY, value=DB_VERSION))
             session.commit()
 
-            # check if folder matching current path exists already
+            # add folder for current path
             folder = Folder(
                 path=library_dir,
                 uuid=str(uuid4()),
@@ -571,19 +571,6 @@ class Library:
                 session.add(Version(key=DB_VERSION_CURRENT_KEY, value=DB_VERSION))
                 session.commit()
 
-            # TODO ASSURANCE 2: version check + reordering
-            # check if folder matching current path exists already
-            self.folder = session.scalar(select(Folder).where(Folder.path == library_dir))
-            if not self.folder:
-                folder = Folder(
-                    path=library_dir,
-                    uuid=str(uuid4()),
-                )
-                session.add(folder)
-                session.expunge(folder)
-                session.commit()
-                self.folder = folder
-
             # save backup if patches will be applied
             if loaded_db_version < DB_VERSION:
                 self.library_dir = library_dir
@@ -644,6 +631,18 @@ class Library:
                 logger.info(f"[Library] Library migrated to DB version {DB_VERSION}")
                 self.set_version(DB_VERSION_CURRENT_KEY, DB_VERSION)
 
+            # check if folder matching current path exists already
+            self.folder = session.scalar(select(Folder).where(Folder.path == library_dir))
+            if not self.folder:
+                folder = Folder(
+                    path=library_dir,
+                    uuid=str(uuid4()),
+                )
+                session.add(folder)
+                session.expunge(folder)
+                session.commit()
+                self.folder = folder
+
         # everything is fine, set the library path
         self.library_dir = library_dir
         return LibraryStatus(success=True, library_path=library_dir)