feat: major restructuring in migration to terragrunt

- migrate from individual terraform files to config-driven terragrunt module structure
- add vault_cluster module with config discovery system
- replace individual .tf files with centralized config.hcl
- restructure auth and secret backends as configurable modules
- move auth roles and secret backends to yaml-based configuration
- convert policies from .hcl to .yaml format, add rules/auth definition
- add pre-commit hooks for yaml formatting and file cleanup
- add terragrunt cache to gitignore
- update makefile with terragrunt commands and format target

policies/pki_int/issue/servers_default.hcl

@@ -1,3 +0,0 @@
-path "pki_int/issue/servers_default" {
-  capabilities = ["update"]
-}

policies/pki_int/issue/servers_default.yaml

@@ -0,0 +1,11 @@
+# Allow issuing server certificates from servers_default role
+---
+rules:
+  - path: "pki_int/issue/servers_default"
+    capabilities:
+      - update
+
+auth:
+  k8s/au/syd1:
+    - huntarr-default
+    - cert_manager_issuer