fix: be more explicit about *_VERSION (tag, branch) and *_SHA

[wdconinc]

Briefly, what does this PR introduce?

We are writing a default read-only mirror with

spack mirror add --scope site --unsigned ghcr-${SPACK_VERSION} oci://ghcr.io/eic/spack-${SPACK_VERSION}

but when we pass SPACK_VERSION as a sha that's not the right location.

This PR ensures that the *_VERSION and *_SHA build arguments are both accepted, and makes it clearer which is which.

What kind of change does this PR introduce?

• Bug fix (issue: incorrect default read-only mirror)
• New feature (issue #__)
• Documentation update
• Other: __

[Copilot]

Pull request overview

This pull request addresses a critical bug in the mirror path construction by distinguishing between version identifiers (branch/tag names) and commit SHA values. When SPACK_VERSION or similar variables were passed as commit SHAs, the buildcache mirror URLs would be incorrect (e.g., oci://ghcr.io/eic/spack-<sha> instead of oci://ghcr.io/eic/spack-<version>).

Key Changes:

• Introduced separate *_SHA build arguments alongside existing *_VERSION arguments across all Dockerfiles and CI configurations
• Modified git checkout commands to use ${*_SHA:-${*_VERSION}} fallback pattern, preferring SHA when available
• Updated CI pipelines to resolve git references and pass both VERSION and SHA as separate build arguments

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 5 comments.

File	Description
containers/debian/Dockerfile	Added *_SHA ARG declarations for SPACK, SPACKPACKAGES, KEY4HEPSPACK, and EICSPACK; updated git checkout commands to use SHA with VERSION fallback
containers/eic/Dockerfile	Renamed *_VERSION to *_SHA for EDM4EIC, EICRECON, EPIC, JUGGLER, BENCHMARK, and CAMPAIGNS; updated git checkout commands with default fallbacks
.gitlab-ci.yml	Added *_SHA build arguments alongside *_VERSION; updated to resolve git refs separately for both values
.github/workflows/build-push.yml	Added SHA output variables alongside VERSION; updated build-args to pass both SHA and VERSION values

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[Copilot]

Pull request overview

Copilot reviewed 4 out of 4 changed files in this pull request and generated no new comments.

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[veprbl]

Looks good