fix: pin GitHub Actions to immutable commit SHAs

refactor: rebrand to Kafka Backup Operator and change CRD API group

fix: add chart-testing CI values for helm-charts lint-test

fix: add proper OpenAPI types to pass-through CRD fields

fix: revert to HELM_CHARTS_PAT secret for helm-charts repo access

fix: use GIT_ORG_REPO_TAG secret for helm-charts repo access

Update Helm install docs to use OSO helm-charts repo and bump CI action versions

fix: bump Rust to 1.88 for home crate MSRV compatibility

fix: Dockerfile user creation and track Cargo.lock

fix: use ASCII-safe characters in README diagrams

feat: initial implementation of strimzi-backup-operator