feat: enhance agent sharing functionality and UI improvements

- Added shared agents state management in Navigation and AgentsList components.
- Implemented fetching and displaying shared agents in the AgentsList.
- Introduced functionality to hide shared agents with appropriate API integration.
- Updated the SharedAgent component layout for better UI consistency.
- Improved error handling in conversation fetching logic.
- Added new API endpoint for hiding shared agents.
- Updated Redux slice to manage shared agents state.
- Refactored AgentCard and AgentSection components for better code organization and readability.

frontend/src/agents/SharedAgent.tsx

@@ -181,7 +181,7 @@ export default function SharedAgent() {
             }
           />
         </div>
-        <div className="flex w-[95%] max-w-[1500px] flex-col items-center gap-4 pb-2 md:w-9/12 lg:w-8/12 xl:w-8/12 2xl:w-6/12">
+        <div className="flex w-[95%] max-w-[1500px] flex-col items-center pb-2 md:w-9/12 lg:w-8/12 xl:w-8/12 2xl:w-6/12">
           <MessageInput
             value={input}
             onChange={(e) => setInput(e.target.value)}