Fix build-docker GHCR tag generation for mixed-case repository names

[Copilot]

build-docker in CI/CD failed because image tags were derived from ${{ github.repository }}, which preserves case (Mohawk-Inference-Engine) and produces invalid GHCR tag paths. This PR normalizes repository casing once and reuses the normalized value for all Docker publish tags.

• Root cause addressed

  • GHCR/Docker requires lowercase repository components in image tags.
  • Existing tags used ${{ github.repository }} directly, causing invalid tag ... repository name must be lowercase.

• Workflow change

  • Added a normalization step in build-docker:
    • computes IMAGE_REPO=ghcr.io/${GITHUB_REPOSITORY,,}
    • exports it via $GITHUB_ENV
  • Replaced hardcoded tag prefixes in both CPU and CUDA image builds with ${{ env.IMAGE_REPO }}.

• Impact

  • Keeps tag construction dynamic across owner/repo changes.
  • Ensures both mohawk-server and mohawk-server-cuda publish paths remain GHCR-compliant.

- name: Normalize image repository path
  run: echo "IMAGE_REPO=ghcr.io/${GITHUB_REPOSITORY,,}" >> "$GITHUB_ENV"

# ...
tags: |
  ${{ env.IMAGE_REPO }}/mohawk-server:latest
  ${{ env.IMAGE_REPO }}/mohawk-server:${{ github.sha }}