refactor: restructure as burnrate-ios + burnrate-macos with xcodegen

feat: SVG flames, new app icon, video blocking, widget polish

fix: lowercase title, better labels, flame orientation, widget previews

feat: fix post-login navigation, video blocking, flame widgets

feat: add app icon, iOS widget, usage link, rename to Burnrate

feat: implement WKWebView-based usage polling with menu bar widget

Initial Commit