feat(orchestrator): MS23 per-agent message history and SSE stream (#702)

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

apps/orchestrator/src/api/agents/dto/get-messages-query.dto.ts

@@ -0,0 +1,17 @@
+import { Type } from "class-transformer";
+import { IsInt, IsOptional, Max, Min } from "class-validator";
+
+export class GetMessagesQueryDto {
+  @IsOptional()
+  @Type(() => Number)
+  @IsInt()
+  @Min(1)
+  @Max(200)
+  limit = 50;
+
+  @IsOptional()
+  @Type(() => Number)
+  @IsInt()
+  @Min(0)
+  skip = 0;
+}