Docs: assorted corrections and clarifications
Multiple documentation edits to correct values, clarify behavior, and tighten wording across the wiki. Notable changes: update installer/localization counts; clarify Backgroundog audio/timing fields and media-session semantics; add Cache subfolders (SignalT, Content) and cache details; fix memory unit reporting (GiB) and other unit notes; adjust many settings defaults (BackdropType=None, Update: Server=Soferity, Module=Downloader, Extension=Executable, AutoType default); document silent-uninstall is broken; refine engine/config filenames and mpv defaults; various UX/command/alias clarifications and minor wording fixes.
Update docs: Portal toolbar is top toolbar
Replace references to the Portal footer toolbar with the top toolbar across documentation. Adjust related wording (search box, settings gear, theme toggle, Display Preferences, Wallpaper Cycling, Create dialog, screenshots) to reflect the toolbar being on the top navigation bar. Updated pages: Choosing-Engines, Create-Step-By-Step, Getting-Help, Managing-Library, Multi-Monitor, Portal-Interface-Tour, Quick-Start, README, Settings-General, Settings-Overview, Settings-Performance, Settings-Personal, Theme-Tray-Startup, Using-Store, Wallpaper-Cycling. These changes keep the docs consistent with the Portal UI relocation.