Enable additional Renovate package managers for this repo

Context

As part of the org-wide Renovate rollout for GitHub Actions
(announcement),
this repo got a Renovate config in #264 that is deliberately scoped to
GitHub Actions only:

// .github/renovate.json5
enabledManagers: ["github-actions"],

Every other built-in manager (npm, cargo, pip, docker, ...) was disabled during
rollout to avoid flooding repos with project-specific upgrade PRs that teams
didn't opt into.

What to do

The rollout is done — this repo's maintainers now own the Renovate config.
Please review which package managers
are relevant here and enable them, e.g.:

enabledManagers: ["github-actions", "npm"],

Then add packageRules to match how this repo wants updates batched/scheduled
(see the existing github-actions rule in the config as a reference).

If this repo previously used Dependabot for these ecosystems, prefer moving
them into Renovate so we keep one tool and one PR style — but that call is
yours.

Questions / DevOps support: ask in #devops or ping @glokos.

Start with .github/renovate.json5 and read the existing GitHub Actions packageRule. Review the repository for package managers relevant to this repo, then configure the selected managers and add matching packageRules. Done means the Renovate configuration reflects the maintainers’ chosen ecosystems, update grouping, and schedule.