archive: prune stale dirs, move actual content to docs/

Deleted stale (Python-era artifacts, superseded by DB):
- archive/oikos-cards/ (46 files, predecessor to DB entity graph)
- archive/ledger/ (5-line JSONL fragment, superseded by DB audit log)

Moved to docs/ (actual, current architecture docs):
- docs/infrastructure/ — 12 infrastructure docs (network, DNS, mesh,
  SSH, ingress, media-permissions, backups, homelab-context, auto-deploy,
  VPS-hardening, monitoring, check-lifecycle)
- docs/secrets/ — secrets README and rotation runbook
- docs/GLOSSARY.md — 28-term homelab glossary

Added STALE.md markers to hermes-plans/ and secrets-issuance/.
Added MOVED.md pointers in archive sources.
Updated docs/index.md to include new paths.

archive/hermes-plans/STALE.md

@@ -0,0 +1,5 @@
+# Stale — historical reference only
+
+These are Hermes agent planning documents from June–July 2026. All plans were
+executed or superseded. Retained for narrative context on why decisions were
+made. Not actively maintained.