[VS Code] Define and validate Aspire support in remote workspaces

### Is there an existing issue for this?

- [x] I have searched the existing issues

### Is your feature request related to a problem? Please describe the problem.

Aspire is commonly used through Remote SSH, Dev Containers, WSL, and Codespaces, but the extension does not currently define or validate a complete remote-workspace contract.

Remote workspaces split responsibilities across the local editor, remote extension host, Aspire CLI, AppHost, container runtime, dashboard browser, and language debuggers. Without an explicit model, failures appear as unrelated path, TTY, certificate, port-forwarding, AppHost-selection, debugger-child-session, or teardown problems.

Existing examples include:

- #17354
- #19290
- #19342

### Describe the solution you'd like

Define and validate the Aspire VS Code remote-workspace experience.

The support model should specify where each component runs and how the extension resolves:

- Aspire CLI installation and executable paths.
- Workspace and AppHost paths and URI authorities.
- AppHost discovery and persisted selection.
- Container runtime availability.
- Dashboard URL forwarding and browser launch behavior.
- Resource debugger availability and child-session ownership.
- Stop, detach, cancellation, and process-tree cleanup.

Completion criteria:

- Document the supported behavior and known requirements for Remote SSH, Dev Containers, WSL, and Codespaces.
- Add automated coverage for the remote-capable scenarios that can run in CI, including at least AppHost discovery, run/debug, dashboard access, and teardown.
- Add focused tests for local/remote path and URI handling where full environment automation is not practical.
- Maintain a repeatable validation checklist for supported scenarios that cannot run in CI.
- Surface actionable errors when a required CLI, debugger, container runtime, certificate, port forward, or remote capability is unavailable.
- Ensure extension-managed and externally started AppHosts are stopped or detached according to their original ownership.

### Additional context

This issue is a support-definition and validation tracker. The concrete bugs above should remain separate sub-issues with their own reproductions and fixes.