[Feature] Watchlist feature

[UncertainMongoose]

Is your feature request related to a problem? Please describe.
No, it is not related to a problem.

Describe the solution you'd like
There should be a watchlist like on most, if not all, streaming services including paid ones (Netflix, HBO, etc.) and self-hosted (e.g. Plex). I, like many Stash users, have thousands of videos. In the course of adding/tagging them, there are a few that really stand out as ones I want to watch sooner rather than later. Right now, I have a tag called 0 - Queue but there should be an intentional feature that appears in a similar manner to the "recently added" section on the Stash home page.

[ariv-x]

What about adding them to a group?

Otherwise, for this really to be useful, it needs some kind of algorithmic underpinning. An AI model would probably be overkill, but for this to be really useful, there should be something which weighs:

• watch count of the video in question
• performer rating / favorites / o-count
• performer tags (performer has favorite tags, but also deeper: does this performer have tags matching other highly-rated performers?)
• tag favorites
• ratings, watches, and o-count for other scenes with similar tags
• other metadata (length, video quality...)

There could even be one automatic list for recommendations from unwatched or rarely-watched videos and a separate one for "favorites" (highly rated and watched a lot but not in the past month, say).

[echo6ix]

This might be something that could potentially be incorporated into groups? #4905

It seems like the groups concept is still baking in the oven so I'd drop a message there about watchlist functionality.

I personally find if you can frame your concept in a way to show multiple use-cases then that increases the chances of adoption. Like advocating for something like "smart groups", where you can define dynamic parameters (filters) for custom groups. Hence you could make a Watchlist group where you can add items to it manually, but also where a condition that removes items from the group if it play count > 0 since it was added to the group.