docs: remove redundant cards from mobile client homepage

- Deleted the 'Features', 'Architecture', and 'Developer Guides' cards from the mobile client homepage.
- These sections are already accessible via the sidebar, making the cards redundant.

Author: fulleni

src/content/docs/mobile-client/index.mdx

@@ -16,16 +16,4 @@ The Mobile Client is a feature-rich, cross-platform mobile app built with Flutte
 		Learn how to build and deploy the mobile app to the app stores.
 		[Read more →](/docs/mobile-client/deployment/)
 	</Card>
-	<Card title="Features" icon="puzzle">
-		Explore the key features, from the dynamic feed to user personalization.
-		[Read more &rarr;](/docs/mobile-client/features/)
-	</Card>
-	<Card title="Architecture" icon="tree-structure">
-		Understand the architecture, state management, and navigation patterns.
-		[Read more &rarr;](/docs/mobile-client/architecture/)
-	</Card>
-	<Card title="Developer Guides" icon="document">
-		Practical guides for developers on theming, customization, and localization.
-		[Read more &rarr;](/docs/mobile-client/guides/)
-	</Card>
 </CardGrid>