build(dockerfile): use multi-stage build; reduce size by ~28%

[Fdawgs]

closes #1414

Checklist

• Commit message adheres to the Conventional commits style, following the @commitlint/config-conventional config

[coveralls]

Pull Request Test Coverage Report for Build 8899632244

Warning: This coverage report may be inaccurate.

This pull request's base commit is no longer the HEAD commit of its target branch. This means it includes changes from outside the original pull request, including, potentially, unrelated coverage changes.

• For more information on this, see Tracking coverage changes with pull request builds.
• To avoid this issue with future PRs, see these Recommended CI Configurations.
• For a quick fix, rebase this PR at GitHub. Your next report should be accurate.

Details

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 100.0%

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Totals
Change from base Build 8720582098:	0.0%
Covered Lines:	668
Relevant Lines:	668

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💛 - Coveralls