feat: added the steam-protondb-plugin

[cecilia-sanare]

ProtonDB Badges

Adds ProtonDB badges to the individual Store and Library pages!

Store	Library

Task Checklist

Developer

• I am the original author or an authorized maintainer of this plugin.
• I have complied with all license requirements for the libraries used, including providing appropriate notices where necessary.
• My plugin is fully open source and does not depend on any external paid services, except for widely trusted and well-known platforms. Additionally, neither I nor anyone associated with me profits from any such services.

Plugin Functionality

• I have tested the plugin on both the Stable and Beta Steam update channels.
• My plugin is unique, or provides additional or alternative functionality to plugins already on the store.

Backend Configuration

• Yes: I use a standard Millennium lua backend in my plugin.
• No: I use custom binaries that or rely on other FOSS projects that aren't written directly using Millennium's python backend.

Community Contribution

• I have tested and left feedback on two other plugin pull requests.
• I have added links to those feedback comments in this PR.

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Testing Instructions

• Verified by a third party on Steam Client Stable.
• Verified by a third party on Steam Client Beta.

[shdwmtr]

Doesn't this do the same thing? (I don't know much about proton-db, so I could be wrong)

[cecilia-sanare]

The primary difference is where the information comes from actually!

The "Steam Deck Compatibility" is coming from Valve themselves
whereas the ProtonDB information is fed by community reports!

This leads to ProtonDB being more up to date then the Steam Deck Compatibility information.
In addition ProtonDB is just generally incredibly useful on linux since it'll also tend to have workarounds even for games that aren't as well supported.