fix(web): fix Theme Custom CSS endpoint requiring the user to be logged in as the server admin (#4633)

* fix custom css requiring the user to be the admin and logged in

* move theme api to custom endpoint

* add e2e test

server/src/domain/server-info/server-info.dto.ts

@@ -1,5 +1,6 @@
 import { FeatureFlags, IServerVersion } from '@app/domain';
 import { ApiProperty, ApiResponseProperty } from '@nestjs/swagger';
+import { SystemConfigThemeDto } from '../system-config/dto/system-config-theme.dto';
 
 export class ServerPingResponse {
   @ApiResponseProperty({ type: String, example: 'pong' })
@@ -79,6 +80,10 @@ export class ServerMediaTypesResponseDto {
   sidecar!: string[];
 }
 
+export class ServerThemeDto {
+  theme!: SystemConfigThemeDto;
+}
+
 export class ServerConfigDto {
   oauthButtonText!: string;
   loginPageMessage!: string;

server/src/domain/server-info/server-info.service.ts

@@ -70,6 +70,11 @@ export class ServerInfoService {
     return this.configCore.getFeatures();
   }
 
+  async getTheme() {
+    const { theme } = await this.configCore.getConfig();
+    return { theme };
+  }
+
   async getConfig(): Promise<ServerConfigDto> {
     const config = await this.configCore.getConfig();