feat: OpenRouter Support & Improve Model Fetching ⇆ (#936)

* chore(ChatGPTClient.js): add support for OpenRouter API
chore(OpenAIClient.js): add support for OpenRouter API

* chore: comment out token debugging

* chore: add back streamResult assignment

* chore: remove double condition/assignment from merging

* refactor(routes/endpoints): -> controller/services logic

* feat: add openrouter model fetching

* chore: remove unused endpointsConfig in cleanupPreset function

* refactor: separate models concern from endpointsConfig

* refactor(data-provider): add TModels type and make TEndpointsConfig adaptible to new endpoint keys

* refactor: complete models endpoint service in data-provider

* refactor: onMutate for refreshToken and login, invalidate models query

* feat: complete models endpoint logic for frontend

* chore: remove requireJwtAuth from /api/endpoints and /api/models as not implemented yet

* fix: endpoint will not be overwritten and instead use active value

* feat: openrouter support for plugins

* chore(EndpointOptionsDialog): remove unused recoil value

* refactor(schemas/parseConvo): add handling of secondaryModels to use first of defined secondary models, which includes last selected one as first, or default to the convo's secondary model value

* refactor: remove hooks from store and move to hooks
refactor(switchToConversation): make switchToConversation use latest recoil state, which is necessary to get the most up-to-date models list, replace wrapper function
refactor(getDefaultConversation): factor out logic into 3 pieces to reduce complexity.

* fix: backend tests

* feat: optimistic update by calling newConvo when models are fetched

* feat: openrouter support for titling convos

* feat: cache models fetch

* chore: add missing dep to AuthContext useEffect

* chore: fix useTimeout types

* chore: delete old getDefaultConvo file

* chore: remove newConvo logic from Root, remove console log from api models caching

* chore: ensure bun is used for building in b:client script

* fix: default endpoint will not default to null on a completely fresh login (no localStorage/cookies)

* chore: add openrouter docs to free_ai_apis.md and .env.example

* chore: remove openrouter console logs

* feat: add debugging env variable for Plugins

client/src/utils/getDefaultEndpoint.ts

@@ -0,0 +1,54 @@
+import type { TConversation, TPreset, TEndpointsConfig } from 'librechat-data-provider';
+import getLocalStorageItems from './getLocalStorageItems';
+
+type TConvoSetup = Partial<TPreset> | Partial<TConversation>;
+
+type TDefaultEndpoint = { convoSetup: TConvoSetup; endpointsConfig: TEndpointsConfig };
+
+const defaultEndpoints = [
+  'openAI',
+  'azureOpenAI',
+  'bingAI',
+  'chatGPTBrowser',
+  'gptPlugins',
+  'google',
+  'anthropic',
+];
+
+const getEndpointFromSetup = (convoSetup: TConvoSetup, endpointsConfig: TEndpointsConfig) => {
+  const { endpoint: targetEndpoint } = convoSetup || {};
+  if (targetEndpoint && endpointsConfig?.[targetEndpoint]) {
+    return targetEndpoint;
+  } else if (targetEndpoint) {
+    console.warn(`Illegal target endpoint ${targetEndpoint} ${endpointsConfig}`);
+  }
+  return null;
+};
+
+const getEndpointFromLocalStorage = (endpointsConfig: TEndpointsConfig) => {
+  try {
+    const { lastConversationSetup } = getLocalStorageItems();
+
+    return (
+      lastConversationSetup.endpoint &&
+      (endpointsConfig[lastConversationSetup.endpoint] ? lastConversationSetup.endpoint : null)
+    );
+  } catch (error) {
+    console.error(error);
+    return null;
+  }
+};
+
+const getDefinedEndpoint = (endpointsConfig: TEndpointsConfig) => {
+  return defaultEndpoints.find((e) => Object.hasOwn(endpointsConfig ?? {}, e)) ?? 'openAI';
+};
+
+const getDefaultEndpoint = ({ convoSetup, endpointsConfig }: TDefaultEndpoint) => {
+  return (
+    getEndpointFromSetup(convoSetup, endpointsConfig) ||
+    getEndpointFromLocalStorage(endpointsConfig) ||
+    getDefinedEndpoint(endpointsConfig)
+  );
+};
+
+export default getDefaultEndpoint;