🎯 refactor: Centralize Agent Model Handling Across Conversation Lifecycle (#10956)

* refactor: Implement clearModelForNonEphemeralAgent utility for improved agent handling

- Introduced clearModelForNonEphemeralAgent function to manage model state for non-ephemeral agents across various components.
- Updated ModelSelectorContext to initialize model based on agent type.
- Enhanced useNavigateToConvo, useQueryParams, and useSelectMention hooks to clear model for non-ephemeral agents.
- Refactored buildDefaultConvo and endpoints utility to ensure proper handling of agent_id and model state.
- Improved overall conversation logic and state management for better performance and reliability.

* refactor: Enhance useNewConvo hook to improve agent conversation handling

- Added logic to skip access checks for existing agent conversations, utilizing localStorage to restore conversations after refresh.
- Improved handling of default endpoints for agents based on user access and existing conversation state, ensuring more reliable conversation initialization.

* refactor: Update ChatRoute and useAuthRedirect to include user roles

- Enhanced ChatRoute to utilize user roles for improved conversation state management.
- Modified useAuthRedirect to return user roles alongside authentication status, ensuring roles are available for conditional logic in ChatRoute.
- Adjusted conversation initialization logic to depend on the loaded roles, enhancing the reliability of the conversation setup.

* refactor: Update BaseClient to handle non-ephemeral agents in conversation logic

- Added a check for non-ephemeral agents in BaseClient, modifying the exceptions set to include 'model' when applicable.
- Enhanced conversation handling to improve flexibility based on agent type.

* test: Add mock for clearModelForNonEphemeralAgent in useQueryParams tests

- Introduced a mock for clearModelForNonEphemeralAgent to enhance testing of query parameters related to non-ephemeral agents.
- This addition supports improved test coverage and ensures proper handling of model state in relevant scenarios.

* refactor: Simplify mocks in useQueryParams tests for improved clarity

- Updated the mocking strategy for utilities in useQueryParams tests to use actual implementations where possible, while still suppressing test output for the logger.
- Enhanced the mock for tQueryParamsSchema to minimize complexity and avoid unnecessary validation during tests, improving test reliability and maintainability.

* refactor: Enhance agent identification logic in BaseClient for improved clarity

* chore: Import Constants in families.ts for enhanced functionality

client/src/store/families.ts

@@ -1,4 +1,5 @@
 import { useEffect } from 'react';
+import { createSearchParams } from 'react-router-dom';
 import {
   atom,
   selector,
@@ -13,9 +14,13 @@ import {
 import { LocalStorageKeys, Constants } from 'librechat-data-provider';
 import type { TMessage, TPreset, TConversation, TSubmission } from 'librechat-data-provider';
 import type { TOptionSettings, ExtendedFile } from '~/common';
+import {
+  clearModelForNonEphemeralAgent,
+  createChatSearchParams,
+  storeEndpointSettings,
+  logger,
+} from '~/utils';
 import { useSetConvoContext } from '~/Providers/SetConvoContext';
-import { storeEndpointSettings, logger, createChatSearchParams } from '~/utils';
-import { createSearchParams } from 'react-router-dom';
 
 const latestMessageKeysAtom = atom<(string | number)[]>({
   key: 'latestMessageKeys',
@@ -101,9 +106,12 @@ const conversationByIndex = atomFamily<TConversation | null, string | number>({
         }
 
         storeEndpointSettings(newValue);
+
+        const convoToStore = { ...newValue };
+        clearModelForNonEphemeralAgent(convoToStore);
         localStorage.setItem(
           `${LocalStorageKeys.LAST_CONVO_SETUP}_${index}`,
-          JSON.stringify(newValue),
+          JSON.stringify(convoToStore),
         );
 
         const disableParams = newValue.disableParams === true;