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/pages/AdminApps.tsx

@@ -440,19 +440,23 @@ export default function AdminApps() {
 
       {/* Platform Tabs */}
       <div className="flex flex-wrap gap-2">
-        {PLATFORMS.map((platform) => (
-          <button
-            key={platform}
-            onClick={() => setSelectedPlatform(platform)}
-            className={`rounded-lg px-4 py-2 text-sm font-medium transition-colors ${
-              selectedPlatform === platform
-                ? 'bg-accent-500 text-white'
-                : 'bg-dark-800 text-dark-300 hover:bg-dark-700'
-            }`}
-          >
-            {PLATFORM_LABELS[platform]}
-          </button>
-        ))}
+        {PLATFORMS.map((platform) => {
+          const platformSvgKey = remnaWaveConfig?.platforms?.[platform]?.svgIconKey;
+          return (
+            <button
+              key={platform}
+              onClick={() => setSelectedPlatform(platform)}
+              className={`flex items-center gap-2 rounded-lg px-4 py-2 text-sm font-medium transition-colors ${
+                selectedPlatform === platform
+                  ? 'bg-accent-500 text-white'
+                  : 'bg-dark-800 text-dark-300 hover:bg-dark-700'
+              }`}
+            >
+              {renderSvgIcon(svgLibrary, platformSvgKey)}
+              {PLATFORM_LABELS[platform]}
+            </button>
+          );
+        })}
       </div>
 
       {/* Apps List */}