feat: Kubernetes log export ingestion

[leo-aa88]

Summary

Support ingesting Kubernetes-oriented log exports (e.g. kubectl logs bulk capture, node/pod export archives, or common export formats) into raglogs.

Motivation

• README Roadmap lists Kubernetes log export ingestion.
• Bridges gap between cluster debugging and raglogs analysis without a full Loki setup.

Scope (proposal)

• Define supported input(s): e.g. concatenated kubectl logs output, JSON lines from fluent-bit/vector exports, or tarball of .log files.
• Parser adjustments if needed for k8s metadata (namespace, pod, container) → map to service / host / labels.
• CLI docs and examples.

Acceptance criteria

• Documented workflow from a standard K8s export into raglogs ingest with correct service/timestamp parsing.
• Tests for at least one representative export format.

Notes

• May overlap with file adapter if export is “just files”; issue tracks first-class K8s export UX and any parsing conventions.