Add Player Count plugin (playcount-steambrew)

[BarterClub]

New Plugin: Player Count

Repository: https://github.com/BarterClub/playcount-steambrew
Backend: Lua
Description: Displays real-time player counts on game pages in the Steam library.

• Live player count badge on library game pages
• Color-coded status based on player count
• Click to open SteamCharts
• Configurable position via settings panel

Ported from playcount-decky by itsOwen

[NotAmiru]

since he needs a vouch that it works from a third party i can vouch that it works as intended

[shdwmtr]

Don't use raw html <input/> components, there's probably an equivalent in @steambrew/client that does the same thing (I can't remember though). Regardless, we must strictly use Steam's components in plugins.