[franco-mariani]

Stacked on #26 (Drop Ruby 2.7 support), which should merge first. GitHub will retarget this PR to main when #26's branch is deleted.

Every specs job is red even when all specs pass: the old codecov gem uploads from SimpleCov's at_exit inside bundle exec rake, Codecov rejects the tokenless upload (Rate limit reached…), and the process exits 1. Codecov hasn't received an upload since 2023-08-18 (#20), and the codecov gem is deprecated (its repo is archived, last release 0.6.0 in Aug 2021).

This PR drops Codecov instead of reviving it:

• Removes the codecov gem and the Codecov workflow step (and the unused CODECOV_TOKEN env).
• Keeps SimpleCov and adds minimum_coverage 98 in CI (currently 98.73%), so a PR that drops coverage fails the specs job.
• Writes the line coverage to the job summary and uploads the HTML report as a coverage-ruby-<version> artifact.

Supersedes #25, which combined this with the Ruby 2.7 removal.

Follow-ups (separate PRs): Pronto + RuboCop on PRs; dependency and Ruby upgrade (refresh the lockfile, test 3.3/3.4/4.0).

[Copilot]

🟢 Approval recommended

The dependency removal, coverage threshold, and reporting changes are consistent, with no blocking issues identified.

No open issues 🎉

What changed in this PR

Replaces Codecov uploads with a CI-enforced SimpleCov coverage threshold and GitHub Actions reports, removing the failing external upload dependency. This PR builds on #26’s Ruby 2.7 removal.

Changes:

• Removes the Codecov dependency, workflow step, and token configuration.
• Enforces a 98% minimum coverage threshold in CI.
• Adds line coverage to job summaries and uploads HTML reports per Ruby version.

File	Description
spec/​spec_helper.rb	Replaces the Codecov formatter with a CI-only coverage threshold.
Gemfile.lock	Removes Codecov from the locked dependencies.
Gemfile	Removes the Codecov test dependency.
.github/​workflows/​main.yml	Replaces Codecov uploads with coverage summaries and report artifacts.

_{Review effort: Balanced}