Fix OCI composition dependency ordering in simple_oci_test

[avrabe]

Problem

The wac_compose_with_oci rule in //examples/simple_oci_test:simple_app fails during CI builds because it tries to pull OCI components before they are published to the registry.

Error

ERROR: Pulling OCI component greeter for composition failed: Registry error: manifest unknown

Root Cause

The simple_app target uses wac_compose_with_oci to pull components from localhost:5001/test/simple/greeting:v1.0.0, but there's no explicit dependency ensuring that :publish_greeting runs before the composition attempts to pull the component.

Current Workaround

Excluded //examples/simple_oci_test/... from CI builds on both Linux and macOS to prevent build failures.

Proposed Solution

Add explicit dependency mechanism to wac_compose_with_oci rule to ensure OCI components are published before composition attempts to pull them. This could be:

1. Add oci_publish_deps attribute to wac_compose_with_oci rule
2. Modify rule implementation to depend on publish targets
3. Use data dependencies or similar Bazel mechanism

Impact

• OCI composition functionality works when components are pre-published
• CI builds are stable with workaround exclusion
• Full OCI workflow validation is needed for production use