docs: update for sops-to-openbao migration completion

Update CLAUDE.md and README.md to reflect that secrets are now managed
by OpenBao, with sops only remaining for ca. Update migration plans
with sops cleanup checklist and auth01 decommission.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

docs/plans/host-migration-to-opentofu.md

@@ -20,7 +20,7 @@ Hosts to migrate:
 | nix-cache01 | Stateless | Binary cache, recreate |
 | http-proxy | Stateless | Reverse proxy, recreate |
 | nats1 | Stateless | Messaging, recreate |
-| auth01 | Stateless | Authentication, recreate |
+| auth01 | Decommission | No longer in use |
 | ha1 | Stateful | Home Assistant + Zigbee2MQTT + Mosquitto |
 | monitoring01 | Stateful | Prometheus, Grafana, Loki |
 | jelly01 | Stateful | Jellyfin metadata, watch history, config |
@@ -94,8 +94,7 @@ These hosts have no meaningful state and can be recreated fresh. For each host:
 Migrate stateless hosts in an order that minimizes disruption:
 
 1. **nix-cache01** — low risk, no downstream dependencies during migration
-2. **auth01** — low risk
-3. **nats1** — low risk, verify no persistent JetStream streams first
+2. **nats1** — low risk, verify no persistent JetStream streams first
 4. **http-proxy** — brief disruption to proxied services, migrate during low-traffic window
 5. **ns1, ns2** — migrate one at a time, verify DNS resolution between each
 
@@ -168,8 +167,9 @@ OpenTofu/Proxmox. Verify the USB device ID on the hypervisor and add the appropr
 `usb` block to the VM definition in `terraform/vms.tf`. The USB device must be passed
 through before starting Zigbee2MQTT on the new host.
 
-## Phase 5: Decommission jump Host
+## Phase 5: Decommission jump and auth01 Hosts
 
+### jump
 1. Verify nothing depends on the jump host (no SSH proxy configs pointing to it, etc.)
 2. Remove host configuration from `hosts/jump/`
 3. Remove from `flake.nix`
@@ -178,12 +178,37 @@ through before starting Zigbee2MQTT on the new host.
 6. Destroy the VM in Proxmox
 7. Commit cleanup
 
+### auth01
+1. Remove host configuration from `hosts/auth01/`
+2. Remove from `flake.nix`
+3. Remove any secrets in `secrets/auth01/`
+4. Remove from `.sops.yaml`
+5. Remove `services/authelia/` and `services/lldap/` (only used by auth01)
+6. Destroy the VM in Proxmox
+7. Commit cleanup
+
 ## Phase 6: Decommission ca Host (Deferred)
 
 Deferred until Phase 4c (PKI migration to OpenBao) is complete. Once all hosts use the
 OpenBao ACME endpoint for certificates, the step-ca host can be decommissioned following
 the same cleanup steps as the jump host.
 
+## Phase 7: Remove sops-nix
+
+Once `ca` is decommissioned (Phase 6), `sops-nix` is no longer used by any host. Remove
+all remnants:
+- `sops-nix` input from `flake.nix` and `flake.lock`
+- `sops-nix.nixosModules.sops` from all host module lists in `flake.nix`
+- `inherit sops-nix` from all specialArgs in `flake.nix`
+- `system/sops.nix` and its import in `system/default.nix`
+- `.sops.yaml`
+- `secrets/` directory
+- All `sops.secrets.*` declarations in `services/ca/`, `services/authelia/`, `services/lldap/`
+- Template scripts that generate age keys for sops (`hosts/template/scripts.nix`,
+  `hosts/template2/scripts.nix`)
+
+See `docs/plans/completed/sops-to-openbao-migration.md` for full context.
+
 ## Notes
 
 - Each host migration should be done individually, not in bulk, to limit blast radius