feat(mship): add parallel subagents, improve streaming performance (#… #19513

Job	Run time
Detect Version	3s
Migrate Dev DB / Apply Database Migrations	1m 55s
Check Docs Changes	0s
Test and Build	-1s
Migrate DB	-1s
Build AMD64	0s
Process Docs	0s
Build ARM64 (GHCR Only)	0s
Create GHCR Manifests	0s
Create GitHub Release	0s
Build Dev ECR (./docker/db.Dockerfile, ECR_MIGRATIONS)	43s
Build Dev ECR (./docker/app.Dockerfile, ECR_APP)	33s
Build Dev ECR (./docker/realtime.Dockerfile, ECR_REALTIME)	1m 14s
	4m 26s

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