[WIP] Full Rewrite/Refactor

[beebls]

This rewrite

• Extracts all platform agnostic logic (api/backend interop and theme state) into src/backend, which eventually will be published as a separate npm package so that it can be shared between decky and desktop
  • ServerAPI calls (toast/backend method call) are now contained in a "repository" which can be dependency injected to use either decky's serverapi, or the desktop's fetch and react-toastify based solutions
  • Switched to a global zustand store that stores all theme data
  • Use reducer style zustand actions (eg: toggleTheme, changePreset) to take logic out of components
• Switches to using zustand stores for all cross-component state
• Adopts the new Decky Websocket API
• Switches to using classname based styling instead of inline styles
• Removes all old css/js hacks that no longer apply to the latest steam stable/beta
• Moves all .then/.catch logic to async await and try catch
• Moves to using @ style imports in components

Progress

• QAM Tab
• Theme Browser (In Progress)
• Expanded View
• Theme Settings
• Preset Settings
• Plugin Settings (Decky Patches included)
• Credits Page