merge v5.9 (BM bigO fix & UI updates)

[JacksonTheMaster]

This update fixes a substantial bug with the backup manager.

Huge thanks to akirilov (Mens_Rea (Discord)) for the work on this update. Most things you see where developed by @akirilov

This release is strongly recommended for all users, especially anyone who experienced extremely slow backup loading times or uses ZFS/large backup directories. The performance improvement is night-and-day.**

New Features

• Added RoundRobin and CommunityStart world configuration options
• Game server console output can now be automatically logged to file (SSUIlogs/gameserver/)
• Log directory is now created reliably on first start
• added dynamic announcement section to UI with support for fetching and displaying dynamic announcements from external JSON source (github pages) to be able to notify users on the dashboard without the need to update the executable (Update / bug announcements)
• added credits page and credits button and bottom of main dashboard

Major Performance & Stability Fix regarding the Backup Manager

• Completely eliminated the severe O(n²) performance bug in the Backup Manager
  → Previously caused 30–60+ minute load times (or even hours) when users had thousands of backup files, especially on ZFS or slow filesystems.
  → Fixed by pre-computing .save file indices in a single directory pass.
  → Backup list now loads in seconds even with 5000+ files.
• Dropped support for the legacy (pre-terrain-update) save/backup format in the new Backup Manager
  • Starting a pre-terrain dedicated server still works perfectly fine
  • The Backup Manager now strictly enforces / only works with the new terrain system
• Added a very noticeable warning in the config loading when loading preterrain SSUI
• Added a collapsible info banner on the dashboard explaining the change
• Migration of saves (also powered by JacksonTheMaster, the author of SSUI): https://sst.jxsn.dev

Fixes & Polish

• Fixed console auto-scroll breaking when the console was active
• Removed duplicate scrollbar in console window
• Fixed re-advertising to Steam master servers when IP or game version changes
• Minor UI/dashboard improvements and text fixes
• Updated World ID guidance text in world config
• refactored CSS to enhance use of variables for improved theming and consistent styling across UI components
• added silly xmas styling (conditional from 1st of Dec to 10th of Jan)

Version

Now at 5.9.1 (includes internal hotfix 5.8.1 )

[JacksonTheMaster]

@akirilov kindly peer-review this PR since S. is unavail - from my side we are fine here - OK

[akirilov]

LGTM