chore(control-plane): move shared automation to aio-fleet

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Summary

• remove repo-local shared workflows, Trunk config, changelog config, upstream/component TOML, and release/validator shims
• keep app-owned runtime/source/docs/tests plus .aio-fleet.yml
• update docs to point release, validation, registry, catalog, upstream, and Trunk operations at aio-fleet

What changed

• deleted shared GitHub Actions workflows and local Trunk config
• deleted shared release, upstream, template validator, derived validator, and XML Changes scripts
• deleted shared tests for those removed shims
• kept app-specific runtime tests and generator code where applicable

Why

• aio-fleet is now the control plane for shared policy, validation, check-runs, release/changelog generation, registry publishing, catalog sync, upstream monitoring, and Trunk

Validation

• from aio-fleet: python -m aio_fleet validate --all
• from aio-fleet: python -m aio_fleet cleanup-repo --all --verify
• from aio-fleet: python -m aio_fleet control-check --repo unraid-aio-template --sha --event pull_request --repo-path ../unraid-aio-template

Notes

• Draft until aio-fleet PR refactor(fleet): use shared release helper shim #29 is merged and the GitHub App check-run secrets are installed so aio-fleet / required can be posted on this branch.