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.
Add screenshots to Settings pages
Replace “📷 Screenshot needed” placeholders with embedded image links for several Settings docs (General, Other, Overview, Performance, Personal, System, Wallpaper). Adds references to .images/*.png to show each Portal settings page, improving documentation UX and visual guidance.