test(build): add comprehensive test coverage for build.clj refactor

[devin-ai-integration]

Summary

Adds 26 tests (66 assertions) covering all functions in build.clj, which previously had zero test coverage. This was motivated by the recent refactor(build): streamline release workflow commit which made several structural changes:

• Replaced global version/jar-file/pom-file defs with per-call helpers (required-version, jar-file-path, pom-file-path)
• Changed jar/install/deploy signatures from [_] to [opts] with required :version
• Added resolved-clojars-repository helper
• Changed indentation inside the pom-data [:scm ...] vector

What's tested:

• Static defs (lib, class-dir, scm-url, basis)
• pom-data structure, including that SCM children (:connection, :developerConnection, :tag) are still nested inside [:scm ...] after the indentation change
• All private helpers: required-version, jar-file-path, pom-file-path, resolved-clojars-repository
• Public functions clean, jar, install, deploy — orchestration order, argument threading, and error cases
• Behavioral equivalence: path helpers produce the same format as the old global defs

Infrastructure: Adds a :test-build alias in deps.edn, a test-build bb task, and a test_build_runner.clj — mirroring the existing test-db pattern. Build tests are kept separate from bb test / bb verify because they require the :build dependencies.

Review & Testing Checklist for Human

• Verify pom-data SCM nesting in build.clj — The refactor changed indentation on lines 19–22 of build.clj making :connection/:developerConnection/:tag look like they might be siblings of [:scm ...] rather than children. Bracket counting says they're still nested correctly, but visually it's misleading. The pom-data-scm-nesting-is-correct test locks this in — confirm the test matches your intent.
• Check "." in :test-build extra-paths — The project root is added to the classpath so build.clj is loadable. This is scoped only to the :test-build alias and mirrors how -T:build works, but verify you're comfortable with it.
• Confirm build tests should stay out of bb verify — Build tests are in a separate runner (like test-db), so bb test and bb verify do NOT run them. If you want them included in CI / verify, the wiring needs adjustment.
• Run bb test-build locally to confirm the new alias and task work end-to-end.

Notes

• All 76 existing tests still pass (bb test → 0 failures, 0 errors).
• Lint (bb lint) and format check (bb format-check) both pass cleanly.
• The pom-data-scm-tag-defaults-to-HEAD test conditionally skips its "HEAD" assertion when GITHUB_REF_NAME is set in the environment (e.g. in CI).
• All build API calls (b/delete, b/copy-dir, b/write-pom, b/jar, dd/deploy) are mocked via with-redefs — tests verify wiring and argument threading, not that a real jar is produced.
• Rebased onto latest main to resolve conflicts (no code changes from the rebase).

Link to Devin session: https://app.devin.ai/sessions/0c6fb5edb4924d3fa4db87fef3075ccb
Requested by: @hatappo

[devin-ai-integration]

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