Watched Folder - Auto-Import Functionality

Is your feature request related to a problem? Please describe.

When bouncing out to an external editor and then generating a new image file while out in that editor (crop version, edits, etc…)

…or, A workflow that involves dumping new folders/images into a central photo directory structure.

darktable needs functionality to watch a directory (structure) and automatically import new images.

Describe the solution you'd like
Find/Install Picasa 3.9 and see how the folder management works.

I see conversations about File/Folder "Management" - It doesn't need to be that.

It just needs a service that looks within a directory structure for new files, and imports them. When dealing with ~100k+ images, having to manually browse and import every new file or directory added is tedious and very much not fluid.. ESPECIALLY in the case of having edited a photo externally, saved/exported a new version, and then being required to go through the import process to find and import that new file.

Alternatives

I've tried to settle using

dt = import "darktable"
dt.database.import("path/to your/directory")

Which does not solve the new image version use case well, but it does not seem to function on Windows.

If you could build an import functionality that has a button attached, that would even suffice. At least then you wouldn't need to exit the application, or go through the import dialog and rescan an entire directory. You could just have a button, that looks in a designated directory, and scans for new files that aren't already in the database.

Additional context

Start by reviewing darktable's existing import dialog and the dt.database.import workflow mentioned in the issue, including how they identify files already in the database. Define the supported watched-directory behavior, Windows expectations, and whether a manual scan button is sufficient; done means new files and externally generated versions are imported without rescanning unrelated directories.