Add MediaPeeky submodule and configuration (#962)

[lonelyclaud]

Add Media Peeky to Plugin Store

Media Peeky is a plugin based on Decky-PiP, but instead of opening a PiP to see external streams, you can take a look at local screenshots and in the future I plan to support videos as well.
The use case is games where you need to refer to something you've seen in the past, some notes or hint to a solution. You can just take a pic of it and take a look with Media Peeky.

Task Checklist

Developer

• I am the original author or an authorized maintainer of this plugin.
• I have abided by the licenses of the libraries I am utilizing, including attaching license notices where appropriate.

Plugin

• I have verified that my plugin works properly on the Stable and Beta update channels of SteamOS.
• I have verified my plugin is unique or provides more/alternative functionality to a plugin already on the store.

Backend

• No: I am using a custom backend other than Python.
• No: I am using a tool or software from a 3rd party FOSS project that does not have it's dependencies statically linked.
• No: I am using a custom binary that has all of it's dependencies statically linked.

Community

• I have tested and left feedback on two other pull requests for new or updating plugins.
• I have commented links to my testing report in this PR.

Testing

• Tested by a third party on SteamOS Stable or Beta update channel.

[github-actions]

Issues Found

No issues with your PR description were found.

Next Steps

1. If we found any issues above, please edit your pull request description to resolve them and leave a comment saying you've done so.
2. For the quickest review, please see the Community section of the pull request template for how you can help other developers.
3. Once your description is correct, a maintainer will review your pull request as soon as possible.

Thank you for your contribution! If you need any help, please reach out on our Discord server. ❤️

[EMERALD0874]

I have a couple of questions before we do an in-depth review:

1. Was this plugin developed with the assistance of generative AI? If so, to what extent?
2. If this plugin is based on Decky-PiP, why not make these features a PR to that plugin? We would rather have a single feature-rich plugin on the store than multiple niche ones.

[github-actions]

This pull request is stale as no updates or testing reports have been posted within the last 7 days. Please ensure you are actively recruiting testers or resolving the issues discussed. If you do not remove the stale label or comment, this will be closed in 7 days. Please close this pull request if you need more time to resolve issues so we can keep our repo healthy.