fix: unify connection page design with global styles and add platform SVG icons

- Add svgIconKey to RemnawavePlatform and RemnawavePlatformData types
- Render platform OS icons from svgLibrary in AdminApps tabs and Connection page
- Replace platform dropdown with icon pill buttons on connection page
- Use .card class with colored left border for block cards
- Unify all back buttons with AdminBackButton pattern (border + bg)
- Fix app chips and platform tabs to not blend with background (btn-secondary style)
- Use accent outlined style for block action buttons matching original RemnaWave UI
- Use btn-secondary for tutorial button

src/api/adminApps.ts

@@ -118,6 +118,7 @@ export interface RemnawaveApp {
 }
 
 export interface RemnawavePlatform {
+  svgIconKey?: string;
   apps: RemnawaveApp[];
 }