Establish clean homelab infrastructure baseline

Reorganize the brownfield repository, remove retired and generated artifacts, harden ignore rules, and record the GitOps/IaC redesign.

docs/superpowers/RETIRED.md

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+# docs/superpowers — RETIRED 2026-07-28
+
+The `plans/` + `specs/` workflow is no longer used. Its one piece of work is
+**done and live**, so nothing here is pending.
+
+**What it covered:** the 2026-04-18 migration of shared PostgreSQL to
+CloudNativePG on OpenEBS ZFS —
+`specs/2026-04-18-postgresql-cnpg-zfs-migration-design.md` (design) and
+`plans/2026-04-18-postgresql-cnpg-zfs-migration.md` (task-by-task plan).
+
+**Outcome: shipped.** `kubectl get cluster -n shared-db` shows
+`shared-postgresql`, 1 instance, *"Cluster in healthy state"*, 101 days old, with
+`shared-postgresql-1` Running. The authoritative manifests live in
+`../../shared-postgresql/` (`cloudnativepg-cluster.yaml`,
+`shared-postgresql-service.yaml`, `serviceaccount.yaml`), and the dump/restore
+/cutover/rollback runbook is `../../shared-postgresql/migration.md`.
+
+**Why retired:** the format carried agent-workflow scaffolding ("REQUIRED
+SUB-SKILL", checkbox task lists) that only ever suited one migration. Design
+documents now live directly in `docs/` — see `../cicd.md` — and the split that
+matters is:
+
+- `CHANGELOG.md` — what changed, for humans
+- `CLAUDE.md` — traps and procedures, for agents
+- `docs/*.md` — design docs for work not yet built
+- `<service>/README.md` — how a service actually works
+
+The two files are kept for the migration rationale, which is still the best
+record of why CNPG and ZFS were chosen. Nothing reads them automatically.