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 #3 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 the Renovate package-manager documentation linked in the issue. Review this repository's dependency ecosystems, then enable the relevant managers and add packageRules based on the existing GitHub Actions rule; the config should reflect the maintainers' chosen update batching and scheduling.