[ROCm CK] Project Structure & Config

[shumway]

Epic: Project Structure & Config

Port the PoC directory layout into production shape. Review and harden CMakeLists and build configuration.

Deliverables:

• Reviewed and documented directory layout
• Clean CMakeLists with documented build options
• Clear presubmit tests with feature flag that blocks inclusion in releases and release validation.

Blocked by: (none)