Feat/navigate to signup if email does not exist (#540)

* Add userExists route

* Fix demo mode for login

* Improve sign in/up flow

* Remove redundant password length constraint

* Fix test

server/src/core/auth/auth.resolver.ts

@@ -1,4 +1,4 @@
-import { Args, Mutation, Resolver } from '@nestjs/graphql';
+import { Args, Mutation, Query, Resolver } from '@nestjs/graphql';
 import { AuthTokens } from './dto/token.entity';
 import { TokenService } from './services/token.service';
 import { RefreshTokenInput } from './dto/refresh-token.input';
@@ -13,6 +13,8 @@ import {
   PrismaSelector,
 } from 'src/decorators/prisma-select.decorator';
 import { Prisma } from '@prisma/client';
+import { UserExists } from './dto/user-exists.entity';
+import { CheckUserExistsInput } from './dto/user-exists.input';
 
 @Resolver()
 export class AuthResolver {
@@ -21,6 +23,16 @@ export class AuthResolver {
     private tokenService: TokenService,
   ) {}
 
+  @Query(() => UserExists)
+  async checkUserExists(
+    @Args() checkUserExistsInput: CheckUserExistsInput,
+  ): Promise<UserExists> {
+    const { exists } = await this.authService.checkUserExists(
+      checkUserExistsInput.email,
+    );
+    return { exists };
+  }
+
   @Mutation(() => LoginToken)
   async challenge(@Args() challengeInput: ChallengeInput): Promise<LoginToken> {
     const user = await this.authService.challenge(challengeInput);