inventory: move cookies secret to SecretClaim

hackerspace/inventory-extras.yaml

@@ -19,3 +19,13 @@ spec:
     - 'offline_access'
   tokenEndpointAuthMethod: 'client_secret_basic'
   pkce: false
+---
+apiVersion: codemowers.cloud/v1beta1
+kind: SecretClaim
+metadata:
+  name: inventory-cookies
+spec:
+  size: 32
+  mapping:
+    - key: COOKIES_SECRET_KEY
+      value: "%(plaintext)s"