fix(filter): correctly create task positions during filter creation

This fixes a bug where a saved filter would contain many "dead" entries for tasks which are not part of that filter. These entries were "dead" because the filter would not match for them and thus they were not shown.
The problem was caused by a routine during the creation of the filter where all projects from all matching tasks would be used as input for fetching the tasks to add to task_positions.

https://community.vikunja.io/t/not-able-to-move-task-between-buckets-within-a-kanban-view-for-saved-filter/2882/3

pkg/models/task_position.go

@@ -137,6 +137,19 @@ func RecalculateTaskPositions(s *xorm.Session, view *ProjectView, a web.Auth) (e
 	}
 	if view.ProjectID < -1 {
 		tc.ProjectID = 0
+
+		sf, err := getSavedFilterSimpleByID(s, getSavedFilterIDFromProjectID(view.ProjectID))
+		if err != nil {
+			return err
+		}
+
+		opts.filterIncludeNulls = sf.Filters.FilterIncludeNulls
+		opts.filterTimezone = sf.Filters.FilterTimezone
+		opts.filter = sf.Filters.Filter
+		opts.parsedFilters, err = getTaskFiltersFromFilterString(opts.filter, opts.filterTimezone)
+		if err != nil {
+			return err
+		}
 	}
 
 	projects, err := getRelevantProjectsFromCollection(s, a, tc)

pkg/models/tasks.go

@@ -310,7 +310,7 @@ func getRawTasksForProjects(s *xorm.Session, projects []*Project, a web.Auth, op
 		}
 		origOpts := clone.Clone(opts)
 		tasks, totalItems, err = tsSearcher.Search(opts)
-		// It is possible that project views are not yet in Typesnse's index. This causes the query here to fail.
+		// It is possible that project views are not yet in Typesense's index. This causes the query here to fail.
 		// To avoid crashing everything, we fall back to the db search in that case.
 		var tsErr = &typesense.HTTPError{}
 		if err != nil && errors.As(err, &tsErr) && tsErr.Status == 404 {