feat(deploy): add --version flag for image version pinning

[chadcrum]

Summary

• Adds --version flag to deploy-dcm.sh — pin all DCM service images to main, an explicit tag (e.g. v0.1.0-rc.1), or release (auto-resolves latest semver from Quay.io)
• Auto-derives --api-gateway-branch to the matching release branch (e.g. v0.1.0-rc.1 → release/v0.1.0) unless explicitly set via flag or env var
• Version env vars stored as a VERSION_ENV_VARS array constant for maintainability

Test plan

• --version release — resolves tag from Quay, derives branch, all health checks pass
• --version v0.1.0-rc.1 — explicit tag, correct branch derivation, all health checks pass
• --version main — no branch derivation, clones main, all health checks pass
• --api-gateway-branch override respected (both CLI flag and env var)
• --help output includes --version and DCM_VERSION
• ShellCheck clean
• Tested on sealusa12 (full deploy + health check for all three modes)

🤖 Generated with Claude Code

[testetson22]

Could add a dependency check for jq, but it's no biggie.

[chadcrum]

jq is already in the prereq check — check_required_tools git podman podman-compose curl jq runs before the version block gets touched.

[ygalblum]

Since the CI builds new images for every push to main, getting to more than 100 tags is not too far (the Catalog Manager is already 49).
The quay api support another filter: filter_tag_name. However, it does not support regex. So, using it will not remove the need to filter using grep. But, it will reduce the array you get back from the API.

So, it can be:

Suggested change

	local api_url="https://quay.io/api/v1/repository/dcm-project/${QUAY_VERSION_REPO}/tag/?onlyActiveTags=true&limit=100"
	local api_url="https://quay.io/api/v1/repository/dcm-project/${QUAY_VERSION_REPO}/tag/?onlyActiveTags=true&limit=100&filter_tag_name=like:v%"

[chadcrum]

Opened #16 for this — adds filter_tag_name=like:v% to the query in resolve_latest_version().