feat(api): add AdminModule with user and workspace management endpoints (#555)

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

apps/api/src/admin/dto/create-workspace.dto.ts

@@ -0,0 +1,15 @@
+import { IsObject, IsOptional, IsString, IsUUID, MaxLength, MinLength } from "class-validator";
+
+export class CreateWorkspaceDto {
+  @IsString({ message: "name must be a string" })
+  @MinLength(1, { message: "name must not be empty" })
+  @MaxLength(255, { message: "name must not exceed 255 characters" })
+  name!: string;
+
+  @IsUUID("4", { message: "ownerId must be a valid UUID" })
+  ownerId!: string;
+
+  @IsOptional()
+  @IsObject({ message: "settings must be an object" })
+  settings?: Record<string, unknown>;
+}