fix: grant vault deployer access to manage the litellm engine

Applying the litellm mount failed with 403 permission denied on
PUT litellm/config: the deployer identity (tf_vault approle /
woodpecker_terraform_vault k8s role) could enable the mount via
sys/mounts/admin but had no policy covering the engine's own data paths.

Add a litellm/admin policy granting create/read/update/delete on
litellm/config and litellm/roles/*, assigned to the same auth roles as the
other secret-engine admin policies.

config/litellm_secret_backend_role/litellm/rspamd.yaml

@@ -0,0 +1,10 @@
+---
+models:
+  - claude-haiku-4-5
+  - claude-sonnet-4-6
+max_budget: 50
+ttl: 3600      # seconds (1h)
+max_ttl: 86400 # seconds (24h)
+metadata:
+  team: mailfiltering
+  env: prod

config/litellm_secret_backend_role/litellm/team-a.yaml

@@ -1,11 +0,0 @@
-# Role on the "litellm" mount (directory name = backend mount path).
-# Constrains the virtual keys generated from creds/team-a.
-models:
-  - gpt-4
-  - gpt-3.5-turbo
-max_budget: 50
-ttl: 3600      # seconds (1h)
-max_ttl: 86400 # seconds (24h)
-metadata:
-  team: a
-  env: prod

policies/litellm/admin.yaml

@@ -0,0 +1,26 @@
+# Allow management of the LiteLLM secrets engine (config and roles)
+---
+rules:
+  - path: "litellm/config"
+    capabilities:
+      - create
+      - update
+      - read
+      - delete
+  - path: "litellm/roles/*"
+    capabilities:
+      - create
+      - update
+      - delete
+      - read
+      - list
+  - path: "litellm/roles"
+    capabilities:
+      - read
+      - list
+
+auth:
+  approle:
+    - tf_vault
+  k8s/au/syd1:
+    - woodpecker_terraform_vault