B1: Brainstorm Kubernetes health checks in Canopy

[passcod]

Description

This PR captures the brainstorm and planning output for bringing Kubernetes-based Tamanu deployments under Canopy's health-check coverage, rather than any implementation of the checks themselves. It adds:

• A breakdown of the idea into follow-on cards (two research spikes on cluster auth and namespace layout, followed by cards for the cluster registry, server k8s identity, infrastructure checks, harvested database checks, and reachability/cluster-failure handling).
• A working plan document laying out the topology assumptions, key decisions (server-as-target, manual identity selection, new kubernetes check source, Canopy-determined reachability), and open questions still to resolve.
• Corresponding spec updates (monitoring/kubernetes.md, monitoring/checks.md, self-alerts.md, statuses.md) describing the intended behaviour at a high level for the spawned cards to implement against.
• Two new repo skills (draft-card-breakdown, review-testing-notes) used to produce and review this kind of breakdown/plan work, plus the .claude/skills symlink to expose them.

No product code changes are included; this is groundwork for the child cards listed in the breakdown.

Test plan

Docs/planning only — no application behaviour changed, so no functional testing applies. Reviewed the breakdown and plan for internal consistency with the spec updates, and confirmed the new skills follow the existing skill file conventions.