Proposal: add build args to docker-build action

Currently, our `docker-build` action does not support passing --build-arg parameters to the docker build command. This limits our ability to dynamically inject build-time variables such as environment configurations, secrets (via build-time only secrets), or versioning metadata.

Proposal:

Add support for build arguments by introducing an optional build-args input to the action. This input could accept a list or key-value pairs, which the action will forward to the docker build command using --build-arg.

Example usage:

```
with:
build-args: |
ENV=production
VERSION=1.2.3
```

This enhancement would improve flexibility and align the action with common Docker build practices.

Locate the docker-build action definition and the docker build command it invokes. Add the optional build-args input with the proposed ENV=production format, forward each argument as --build-arg, and verify that builds without the input still work.

Written by the indexing model from the issue text.