## Why
Applying the newly-merged litellm mount (#83) failed at apply time with:
```
Error: failed to write litellm config
URL: PUT https://vault.service.consul:8200/v1/litellm/config
Code: 403. * permission denied
```
The deployer identity (`tf_vault` approle / `woodpecker_terraform_vault` k8s role) can enable the mount via `sys/mounts/admin`, but no policy grants it access to the engine's own data paths, so writing the config and roles is denied.
## Changes
- Add `policies/litellm/admin.yaml` granting `create`/`read`/`update`/`delete` on `litellm/config` and `litellm/roles/*` (plus `read`/`list` on `litellm/roles`), assigned to the same auth roles as the other secret-engine admin policies (`tf_vault`, `woodpecker_terraform_vault`).
## Note
The policy attaches to the deployer's auth roles, so it takes effect on the next token issuance — a re-run of the apply (fresh Vault login) will have the permission and can write `litellm/config` and the roles.
Reviewed-on: #84
Co-authored-by: Ben Vincent <ben@unkin.net>
Co-committed-by: Ben Vincent <ben@unkin.net>
## Why
The `vault-plugin-secrets-litellm` engine (mints LiteLLM virtual keys) is registered in Vault, but nothing in this repo declared its mount, config, or roles. This wires in the companion `litellm` provider (`git.unkin.net/unkin/litellmvaultsecret`) so the mount is managed as code alongside the other secret backends.
## Changes
- Add `litellm_secret_backend` module that mounts the engine and writes its config (`base_url`, `request_timeout_seconds`); reads the sensitive `master_key` from KV at `kv/service/vault/<country>/<region>/secret_backend/<path>`, matching the consul/kubernetes backend convention.
- Add `litellm_secret_backend_role` module that manages roles (`models`, `max_budget`, `key_alias_prefix`, `ttl`/`max_ttl` in seconds, `metadata`).
- Register both modules in `vault_cluster` `main.tf` and add typed variables in `variables.tf`.
- Discover `litellm_secret_backend[_role]` YAML in `config.hcl` and pass the maps through the terragrunt inputs.
- Declare the `litellm` provider (pinned `0.1.0`) and a `provider "litellm"` block in the generated root `backend.tf`.
- Add example config for the `litellm` mount and a sample `team-a` role.
## Notes
- Requires the `master_key` KV secret to exist at `kv/service/vault/au/syd1/secret_backend/litellm` before apply (the module reads it, does not create it).
- Assumes provider `git.unkin.net/unkin/litellmvaultsecret` `0.1.0` is published to the artifactapi `terraform-unkin` registry.
Reviewed-on: #83
Co-authored-by: Ben Vincent <ben@unkin.net>
Co-committed-by: Ben Vincent <ben@unkin.net>
unkinben