Modules used filebase64("${path.root}/.git/git-crypt/keys/default")
which breaks with Terragrunt since path.root is now stacks/<service>/
instead of repo root. Changed to accept git_crypt_key_base64 variable
and resolve the path in the stack wrapper.
Generated individual stack directories for all 66 services under stacks/.
Each stack has terragrunt.hcl (depends on platform) and main.tf (thin
wrapper calling existing module). Migrated all 64 active service states
from root terraform.tfstate to individual state files. Root state is now
empty. Verified with terragrunt plan on multiple stacks (no changes).