[Feature Request] Add a tag for Steam Deck compatibility

[ShredderWalnut]

Is your feature request related to a problem? Please describe.
I don't have a dedicated gaming PC and would like to only game on my Steam Deck. Recently I won a game only to find out it's rated Unsupported by Valve, and I indeed could not get it to run.

Describe the solution you'd like.
Add a new tag (or tags) under section 9.2 of ESGST's settings, "Game Categories", which shows the game's Deck compatibility. The data can come from Valve's official rating, and/or ProtonDB's rating.

Describe alternatives you've considered.
Before entering each giveaway, I'll need to either manually scroll down the game's store page to find its rating by Valve, or visit its ProtonDB page.

Additional Context
I believe this will be very useful not only to players like me who primarily/exclusively game on the Deck, but to all Deck owners on SteamGifts too.