Wire API_TOKEN_PEPPERS into NetBox config (#346)

## Why

NetBox 4.6.5 refuses to save v2 API tokens without `API_TOKEN_PEPPERS` ("Unable to save v2 tokens: API_TOKEN_PEPPERS is not defined"), which blocks creating the superuser token the NetBox Vault engine needs (it defaults to v2 tokens). The chart only auto-generates a pepper when it creates the config secret itself; it does not do that while `existingSecret` (`netbox-secret-key`) is set, so the config secret carries no `api_token_peppers` key.

## Changes

- Document `api_token_peppers` on the `netbox-secret-key` VaultStaticSecret: a JSON pepper map `{"1": "<random>"}` seeded once into Vault alongside `secret_key`. VSO syncs every key at the path into the config secret, which the chart already mounts as an optional file into `API_TOKEN_PEPPERS`.
- Add a reloader annotation via `commonAnnotations` so the `netbox` and `netbox-worker` Deployments roll when `netbox-secret-key` changes, picking up the seeded pepper (and any rotated `secret_key`) without a manual restart.

## Follow-up (out of band)

seed the pepper once (rotating it invalidates existing v2 tokens):

```
PEP=$(openssl rand -base64 48 | tr -d '\n')
vault kv patch kv/kubernetes/namespace/netbox/default/netbox-secret-key \
  api_token_peppers="{\"1\": \"$PEP\"}"
```

---------

Co-authored-by: Ben Vincent <neotheo@gmail.com>
Reviewed-on: #346
Co-authored-by: Ben Vincent <ben@unkin.net>
Co-committed-by: Ben Vincent <ben@unkin.net>

apps/base/netbox/vaultstaticsecret.yaml

@@ -19,7 +19,13 @@ spec:
   type: kv-v2
   vaultAuthRef: default
 ---
-# Django SECRET_KEY (key: secret_key). One-time Vault seed.
+# Config secret. Keys:
+#   secret_key         : Django SECRET_KEY (50+ random chars). One-time Vault seed.
+#   api_token_peppers  : JSON object {"1": "<50+ char random>"} used to HMAC-hash
+#                        v2 API tokens. One-time Vault seed — rotating a pepper
+#                        invalidates existing v2 tokens, so set it once.
+# VSO syncs every key at the path into the destination Secret, and the NetBox
+# chart mounts both keys from it (existingSecret) — no explicit key mapping needed.
 apiVersion: secrets.hashicorp.com/v1beta1
 kind: VaultStaticSecret
 metadata:

apps/overlays/au-syd1/netbox/values.yaml

@@ -13,13 +13,24 @@ image:
 # Two web replicas for zero-downtime rollouts (media is RWX, see below).
 replicaCount: 2
 
-# Django SECRET_KEY — existingSecret must contain key: secret_key.
+# Config secret. Must contain key: secret_key (Django SECRET_KEY). Also carries
+# api_token_peppers — a JSON object {"1": "<50+ char random>"} the chart mounts
+# (optional file) into API_TOKEN_PEPPERS; NetBox 4.6 refuses to save v2 tokens
+# without it. The chart only auto-generates a pepper when it creates this secret
+# itself, which it does NOT do while existingSecret is set — so the pepper is
+# seeded into Vault alongside secret_key (see base/vaultstaticsecret.yaml).
 existingSecret: netbox-secret-key
 
 # Bootstrap superuser — existingSecret keys: username, password, email, api_token.
 superuser:
   existingSecret: netbox-superuser
 
+# Roll NetBox (web + worker) when the config secret changes, so a Vault-seeded
+# api_token_peppers (or a rotated secret_key) is picked up without a manual
+# restart. commonAnnotations lands on Deployment metadata, where reloader reads it.
+commonAnnotations:
+  secret.reloader.stakater.com/reload: netbox-secret-key
+
 # Disable the bundled Bitnami subcharts; we bring our own Postgres and Valkey.
 postgresql:
   enabled: false