Rename Aspire Dashboard image to aspire/dashboard family

[IEvangelist]

Summary

• Publish Aspire Dashboard under the dedicated aspire product family: mcr.microsoft.com/aspire/nightly/dashboard on nightly, flowing to mcr.microsoft.com/aspire/dashboard on main.
• Preserve the internal aspire-dashboard identifier, src/aspire-dashboard Dockerfile paths, template/tag-metadata paths, version variables, README filenames, and test traits.
• Supersede Rename Aspire Dashboard image to aspire/dashboard family #7218 with a clean implementation based on the latest nightly; this does not merge or modify José's branch or PR.
• Remove Aspire Dashboard Docker Hub README publication and remove Aspire from unrelated .NET featured/related repository lists.
• Refresh Aspire branding and documentation links to microsoft/aspire and the standalone dashboard documentation.

Aspire 13 compatibility window

Aspire 13 tags continue to syndicate to the legacy MCR repositories so existing users keep receiving servicing and security updates:

• mcr.microsoft.com/dotnet/nightly/aspire-dashboard on this branch
• mcr.microsoft.com/dotnet/aspire-dashboard when flowed to main

Fixed, minor, major, and architecture-specific tags are syndicated. Legacy latest is explicitly emitted from the Aspire 13 major tag rather than canonical latest, so it remains on the v13 servicing line. Focused tests require syndication to be absent once the Aspire major is no longer 13, preventing the alias from carrying into the next major.

This MCR compatibility syndication is separate from Docker Hub publication; no Aspire Docker Hub README or canonical Docker Hub claim is retained.

MCR coordination

• microsoft/mcr#5204 defines the canonical teams/aspire claims, Aspire branding, standalone documentation URL, no Docker Hub syndication, and stable-only cloud syndication.
• microsoft/mcrdocs#48050 provides the canonical stable/nightly Aspire logo, README, and tag-metadata file contract.

Validation

• pwsh ./eng/readme-templates/Get-GeneratedReadmes.ps1 -Branch nightly
• pwsh ./eng/readme-templates/Get-GeneratedReadmes.ps1 -Validate -Branch nightly
• pwsh ./eng/dockerfile-templates/Get-GeneratedDockerfiles.ps1 -Validate -Branch nightly
• 138 pre-build manifest, syndication, static-tag, and test-data tests passed (Category=pre-build&FullyQualifiedName!~GeneratedArtifactTests)

[IEvangelist]

CI triage: the failing Azure Pipelines jobs are a shared nightly baseline issue, not caused by this Aspire change. Across cached and no-cache builds, the .NET 10/11 Resolute package tests expect gcc-16-base while the built runtime/runtime-deps/ASP.NET images contain gcc-14-base, across amd64, arm32, and arm64. The same jobs are failing on unrelated PRs #7336, #7335, #7331, and #7330.

The Aspire-specific README/Dockerfile generation checks and 138 focused manifest, syndication, static-tag, and test-data tests pass. This PR is ready for review; the full matrix should be rerun after the shared Resolute baseline is repaired.

[lbussell]

Shall we close #7218?