feat(api): chat proxy (MS22-P1i) (#615)

Co-authored-by: Jason Woltje <jason@diversecanvas.com>
Co-committed-by: Jason Woltje <jason@diversecanvas.com>

apps/api/src/chat-proxy/chat-proxy.dto.ts

@@ -0,0 +1,25 @@
+import { Type } from "class-transformer";
+import { ArrayMinSize, IsArray, IsNotEmpty, IsString, ValidateNested } from "class-validator";
+
+export interface ChatMessage {
+  role: string;
+  content: string;
+}
+
+export class ChatMessageDto implements ChatMessage {
+  @IsString({ message: "role must be a string" })
+  @IsNotEmpty({ message: "role is required" })
+  role!: string;
+
+  @IsString({ message: "content must be a string" })
+  @IsNotEmpty({ message: "content is required" })
+  content!: string;
+}
+
+export class ChatStreamDto {
+  @IsArray({ message: "messages must be an array" })
+  @ArrayMinSize(1, { message: "messages must contain at least one message" })
+  @ValidateNested({ each: true })
+  @Type(() => ChatMessageDto)
+  messages!: ChatMessageDto[];
+}