docs(guides): add autostart guide

[midwesternrodent]

Description

Add a new guide for how to enable autostart for Sunshine without enabling autologin. This is the significantly revised document from my previous PR #3200

This guide works by first starting a system service that creates an SSH tunnel to the localhost to start sunshine, similar to Eric Dong's guide on Remote SSH headless setup, but we're SSHing from the local machine instead of a remote machine so you don't need to leave the moonlight client to get streaming setup. After you login to SDDM, there is a second user service that kills the first system service, and runs sunshine with the permissions of the graphical desktop; this is to fix the issues I encountered in #3200 where pipewire was not working, and the system tray icon did not appear.

This guide also gives some non-sunshine related advice around configuring SDDM so you don't end up with a situation where the display streaming to moonlight does not have the mouse captured on it.

There are a few caveats to this guide:

1. When you login via moonlight, you will be temporarily disconnected until the next user service starts.
2. I haven't found a way to disable sleep on the login screen, so sometimes the screen can time out and moonlight can't connect if you leave it sit too long. This would happen on Eric Dong's guide as well though.

I have also made some changes to Eric Dong's guide, one just to call out that there is an issue with pipewire audio over SSH and directing people to this guide to fix it.

The second edit, is more of a style / best practices change that I'm more than happy to drop from this PR if anyone disagrees. However, I did change the sections where they're editing a file in sudoers.d to use visudo rather than echoing the edits directly just for the sake of user safety.

I also added some tips to the KDE Plasma (X11, Wayland) section of the app config examples, just to call out how to find the names of the displays with kscreen-doctor since that was a little difficult for me to find online otherwise.

Problems with these documents:
I couldn't figure out how to do internal links properly, so I ended up hardlinking in quite a few areas to docs.lizardbyte.dev, and I imagine that's not the right way to do things. If someone can let me know how you'd like me to do those links, I can get them changed for you so they work better internally.

Because of this issue, I also wasn't able to link to my guide from Eric Dong's guide so once I know how to do the internal links, I'll want to add that just to redirect people.

Also - I didn't want to take away from Eric Dong's voice so I pointed out my authorship of the pipewire issue callout, but I did not call out that I made the visudo change. I don't really care about attribution in that (or any) part, I just wanted to make clear that the comments on pipewire's audio streaming issues over SSH were not from the original author of that guide. If you want me to change that, that's fine by me.

Let me know what I can do to help get this merged or make it more understandable. Thanks!

Screenshot

Issues Fixed or Closed

Type of Change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Dependency update (updates to dependencies)
• Documentation update (changes to documentation)
• Repository update (changes to repository files, e.g. .github/...)

Checklist

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have added or updated the in code docstring/documentation-blocks for new or existing methods/components

[ReenigneArcher]

Thanks for the PR! Before I review this in detail, could you make the max line length of your changes 120 characters?

[midwesternrodent]

Thanks for the PR! Before I review this in detail, could you make the max line length of your changes 120 characters?

Absolutely. I had a little extra time tonight and get them all reduced and fixed some spelling and formatting issues.

If there are any parts you'd like me to condense, please let me know - I fully recognize it's a book.

Do you have any tips on how you'd like me to handle the internal linking? Right now I'm doing things like this which seems wrong based on what I'm seeing in other guides. [Static IP Setup](https://docs.lizardbyte.dev/projects/sunshine/en/latest/about/guides/linux/headless_ssh.html#static-ip-setup)

[ReenigneArcher]

This seems to be great guide, and really informative! I learned a lot by reading all of this (although I haven't run through any of it myself).

My suggestions are mostly to improve formatting and consistency. Thank you!

Edit:

Do you have any tips on how you'd like me to handle the internal linking?

I have some suggestions below on that as well.

[midwesternrodent]

I've reviewed all your suggestions and they look great. Thank you for taking the time to do that, I'll certainly be taking some of your style suggestions to heart for future guides, they're very clean.

I don't want to merge this quite yet, because I remember finding an error in one of my commands the other day so I'm gonna take some time to proofread this once or twice more tomorrow and make sure I caught all of those. I'll let you know when I think it's perfect (or at least good enough).

[ReenigneArcher]

Found a few more things, but this is getting close.

If you want to see the docs rendered, they appear here https://lizardbyte--3287.org.readthedocs.build/projects/sunshine/en/3287/md_docs_2guides.html for your PR.

[midwesternrodent]

I think I've gotten all the issues with the last two proofreads, and we should be good to merge. Let me know if you agree, or if you think there are a few things left to change still. Thanks for all your help in moving this along, I appreciate it!

[ReenigneArcher]

Thanks for working through all these points!

I think these are my final requests.

I reviewed the rendered docs, and everything appears nice there.

[midwesternrodent]

Sounds good, I've accepted all of your suggestions. Let me know if there's anything else!

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarCloud

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 11.13%. Comparing base (f429d34) to head (af3cb10).
Report is 79 commits behind head on master.

Additional details and impacted files

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  Coverage   11.12%   11.13%           
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  Files          99       99           
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  Branches     8023     8023           
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+ Hits         1915     1916    +1     
  Misses      12737    12737           
+ Partials     2559     2558    -1     

Flag	Coverage Δ
Linux	8.42% <ø> (ø)
Windows	5.19% <ø> (ø)
macOS-13	13.60% <ø> (+0.01%)	⬆️
macOS-14	12.59% <ø> (ø)

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see 1 file with indirect coverage changes

[ReenigneArcher]

Thanks for all the changes! This will be merged once all the CI passes