Add deployment roadmap document

[mitchdenny]

Description

Introduces a deployment roadmap document at docs/roadmap/deployment-roadmap.md covering forward-looking investment areas for Aspire's deployment story. This is an aspirational planning document (no code changes) exploring the problem space across four pillars:

1. Compute Environment Completeness — Kubernetes gaps (aspire deploy, Helm/YAML/Kustomize, PVCs, AKS package), Docker/ACA/AppService maintenance
2. Pipeline Generation & Maintenance — Programming model exploration for CI/CD generation (AddGitHubActions, split build/publish, sealed environments, enterprise composability)
3. Make Azure Awesome — Custom domains, per-region fallback, AZD migration, Radius integration
4. Agentic Post-Deployment Operations — Safe agent inspection of deployed environments, operations model, privilege levels

Includes cross-cutting concerns and open questions for further discussion.

Checklist

• Is this feature complete?
  • Yes. Ready to ship.
  • No. Follow-up changes expected.
• Are you including unit tests for the changes and scenario tests if relevant?
  • Yes
  • No
• Did you add public API?
  • Yes
  • No
• Does the change make any security assumptions or guarantees?
  • Yes
  • No
• Does the change require an update in our Aspire docs?
  • Yes
  • No

[github-actions]

🚀 Dogfood this PR with:

⚠️ WARNING: Do not do this without first carefully reviewing the code of this PR to satisfy yourself it is safe.

curl -fsSL https://raw.githubusercontent.com/microsoft/aspire/main/eng/scripts/get-aspire-cli-pr.sh | bash -s -- 15594

Or

• Run remotely in PowerShell:

iex "& { $(irm https://raw.githubusercontent.com/microsoft/aspire/main/eng/scripts/get-aspire-cli-pr.ps1) } 15594"

[mitchdenny]

Note there are some hallucinations in this document for example the plain YAML export for Kubernetes and aspire export. This is a first draft using Copilot CLI and needs changes. Just trying to flesh out the skeleton expert more revisions to add correctness and detail.