Migrate release documentation and consumer templates to release-tool ownership

[vitormattos]

Context

Release implementation and documentation are currently split between release-tool, github-workflows, organization workflow templates, and consumer repositories.

Goal

Make this repository authoritative for the release product while keeping organization workflow templates in LibreCodeCoop/.github as the materialized distribution layer.

Scope

• Move or consolidate release product documentation currently maintained in github-workflows.
• Update release integration docs in this repository.
• Update organization templates to consume the new release-tool/actions/* paths.
• Remove release-tool-specific documentation and tests from github-workflows after cutover.
• Preserve the full visible YAML workflows in consumers; do not replace them with reusable workflow callers.

Done when

The release product can be understood, tested and versioned from this repository, while .github contains only the organization-level workflow templates that consume it.

[vitormattos]

Completed.

Release Tool documentation now describes this repository as the owner of release policy, PHP runtime, contracts, and the three public lifecycle Actions (PR #69). LibreSign release documentation was updated in LibreSign/documentation#103.

The organization catalog is documented separately under LibreCodeCoop/.github and only orchestrates/materializes workflows; it no longer owns release behavior.