fix: resolve HCL semicolons and vault-platform dependency cycle

- Replace semicolons with newlines in vault/main.tf variable blocks
  (HCL does not support semicolons)
- Remove dependency "vault" from platform/terragrunt.hcl to break
  cycle (vault already depends on platform)

stacks/platform/terragrunt.hcl

@@ -8,7 +8,5 @@ dependency "infra" {
   skip_outputs = true
 }
 
-dependency "vault" {
-  config_path  = "../vault"
-  skip_outputs = true
-}
+# NOTE: platform cannot depend on vault (vault depends on platform → cycle).
+# Vault KV must be populated before platform apply. Use: vault first, then platform.