style: Enhance UI components in Agents feature for improved layout and aesthetics

[AshAnand34]

• Adjusted padding and margins in AgentsInterfaceV2 for better spacing.
• Updated TabsList and TabsTrigger styles for a more cohesive look.
• Enhanced loading states in Suspense components with improved visual feedback.
• Refined AgentCard and TemplateCard components with updated styles and hover effects.
• Improved PageHeader layout and typography for better readability.
• Enhanced search input styles across various components for consistency.

[vercel]

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