Should merge deps layer architectures in tfvars generation

[ccfontes]

Fix working for my arm64 lambdas.

Commit and description are AI generated.

Problem
Blambda’s terraform generation dropped deps-layer-compatible-architectures. The when deps-layer-name form returned only the last map in the body, so the architectures map was evaluated then discarded. As a result, deps layers were emitted with an empty architectures list, defaulting to x86_64 in AWS and breaking ARM64 lambdas.

Error message:

  /opt/bootstrap: line 27: /opt/bb: cannot execute binary file
  Runtime.ExitError: Runtime exited with error: exit status 126

Repro

1. Unpatched blambda v0.2.0; lambda configured for ARM64 (e.g., :bb-arch "arm64" in its bb.edn) and Terraform lambda set to ["arm64"].
2. Run the normal blambda generation (write-config/deploy hook).
3. Check the generated blambda.auto.tfvars: runtime shows ["arm64"] but deps_layer_compatible_architectures is empty.
4. Apply Terraform; the deps layer publishes with the default x86_64.
5. Invoke the ARM64 lambda; it pulls the x86 deps layer and fails:

     /opt/bootstrap: line 27: /opt/bb: cannot execute binary file
     Runtime.ExitError: exit status 126

Fix
Merge the deps-layer maps so architectures are included when skip-compatible-architectures is false:

• In blambda/src/blambda/api/terraform.clj, wrap the deps-layer maps in merge and add the architectures map conditionally.

This ensures generated tfvars include both architectures (or whatever lib/deps-layer-architectures returns) and deploy correctly for ARM64.