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Deleted stale (Python-era artifacts, superseded by DB):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- archive/ledger/ (5-line JSONL fragment, superseded by DB audit log)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/knowledge/infrastructure/MOVED.md

@@ -0,0 +1,20 @@
+# Moved to `docs/infrastructure/`
+
+The infrastructure architecture docs have been moved to
+[`docs/infrastructure/`](../../docs/infrastructure/):
+
+- [network.md](../../docs/infrastructure/network.md)
+- [dns.md](../../docs/infrastructure/dns.md)
+- [mesh.md](../../docs/infrastructure/mesh.md)
+- [ssh-access.md](../../docs/infrastructure/ssh-access.md)
+- [ingress.md](../../docs/infrastructure/ingress.md)
+- [media-permissions.md](../../docs/infrastructure/media-permissions.md)
+- [backups.md](../../docs/infrastructure/backups.md)
+- [homelab-context.md](../../docs/infrastructure/homelab-context.md)
+- [auto-deploy.md](../../docs/infrastructure/auto-deploy.md)
+- [vps-hardening.md](../../docs/infrastructure/vps-hardening.md)
+- [monitoring.md](../../docs/infrastructure/monitoring.md)
+- [oikos-check-lifecycle.md](../../docs/infrastructure/oikos-check-lifecycle.md)
+
+The copies here are kept for archive continuity but are NOT the source of
+truth — update the docs/ copies instead.