[FR]: Support a dedicated folder for recurring parents and/or their occurrences

[raphaelfaouakhiri]

Two related asks:

1. Parent in a subfolder: today, moving a recurring parent into a subfolder of the tasks folder can break materialization — name dedup produces an ambiguous recurrence_parent link and completion fails with occurrence_parent_not_recurring. Parents should resolve regardless of folder.
2. Occurrences folder setting: an option to materialize occurrences into a different folder than the default tasks folder (like archiveFolder, but for occurrences — or a folder template variable). Use case: recurring "obligations" (parents) are configuration, occurrences are the operational to-do items; keeping them in separate folders keeps file lists and non-TaskNotes views clean.