fix(release): trigger on merge-to-main with should_release gate

[kayodebristol]

Problem

Releases stopped org-wide since ~2026-05-11. PR plures/.github#13 fixed version computation (highest-tag reconciliation), but releases still won't fire because every repo's release.yml triggers only on push: tags: ['v*'] + workflow_dispatch.

The release pipeline is what creates and pushes the v* tag. So a tag is an output of a release, never an input on merge-to-main. Result: a circular trigger — nothing pushes a tag on normal merges, so nothing releases. The only start paths are a human clicking Run workflow or hand-pushing a tag = manual dependency (violates automation-first + zero-manual-dependency).

Fix

Add push: branches: [main] (conventional-commit autobump on merge-to-main, the documented model in even-odd-release-versioning.md and the reusable's own USAGE header) plus a concurrency guard. Keep tags: ['v*'] and workflow_dispatch for backward-compat.

No over-release risk: the reusable release-reusable.yml decide step already returns should_release=false for chore/ci/docs-only pushes (git log LAST_TAG..HEAD empty or no feat|fix|perf|refactor), and every downstream job gates on should_release == 'true'. The self-triggered chore(release): bump push re-runs prepare, sees the fresh tag as LAST_TAG, and cleanly no-ops (concurrency guard serializes it).

Validation

• actionlint passes; 0 literal-\n mangling; 0 secret corruption.
• Additive diff (4 insertions), thin caller otherwise byte-identical.

Scope

Mechanical, byte-identical fix across ~70 release-bearing plures repos. This is the canary (chronos). Full findings + sweep list: workspace tmp/release-trigger-findings.md. Do not merge until canary behavior is confirmed on one real merge-to-main.

MSC Alignment: Execution Discipline — restores autonomous, deterministic org-wide releases.

[Copilot]

Pull request overview

This PR updates Chronos’ release workflow to restore autonomous releases by triggering the reusable release pipeline on merge-to-main (instead of only on v* tag pushes), and adds a concurrency guard intended to prevent overlapping release runs.

Changes:

• Add push: branches: [main] so merges to main can initiate releases.
• Add a top-level concurrency group to serialize release workflow runs.