Support nested root-module instances in mixin update task #47

Problem

Our mixin update task assumes a flat root-modules/* layout.

That works for root modules like:

• root-modules/aws-budgets/
• root-modules/tailscale/

But it misses nested deployable instances like:

• root-modules/aws-iam/delegated-tf-role/
• root-modules/aws-iam/primary-tf-role/

Requested change

Please update the mixin sync task so it copies the selected mixin into all deployable root-module directories, including nested ones.

Expected behavior

If a repo contains:

• root-modules/aws-budgets/main.tf
• root-modules/tailscale/main.tf
• root-modules/aws-iam/delegated-tf-role/main.tf
• root-modules/aws-iam/primary-tf-role/main.tf

Then the mixin update task should update the corresponding <mixin>.tf file in all four directories.

Suggested approach

Instead of assuming root-modules/*, find deployable directories by locating main.tf, then copy mixins/<name>.tf.tpl into each directory as <name>.tf.