chore: align repository groups with subproject inventory

[yada]

Summary

• classify api-tooling as delivered tooling
• align DEMONSTRATIONS with the authoritative Demonstration or workshop
  category in SUBPROJECTS.md
• document the source-of-truth relationship in the replication workflow
• use the canonical contribution-guide URL from replicated MAINTAINERS.md

Context

api-tooling remains an active tooling repository used during Microcks
development and testing. It should not be treated as a demonstration.

The inventory also identifies microcks-quarkus-demo and
microcks-testcontainers-dotnet-workshop as demonstration/workshop
repositories, but they were missing from the replication group.

Demonstration repositories do not receive a local CONTRIBUTING.md. The
absolute contribution-guide link keeps replicated MAINTAINERS.md valid in
those repositories.

Validation

• verified that DEMONSTRATIONS exactly matches all 10 corresponding entries
  in SUBPROJECTS.md
• verified that api-tooling is included in DELIVERED_COMPONENTS
• parsed global-replicator.yml successfully
• verified the canonical contribution-guide link
• ran git diff --check

Follow-up

Separate repository PRs will:

• bootstrap the applicable canonical files in api-tooling
• remove files that should not be replicated to the Quarkus demo and .NET
  workshop
• remove the stale workflow from the .NET and Aspire demos

Refs: #97