* Test coverage hardening and parallel-safe refactors
Add focused test coverage for under-tested operational paths, edge branches,
and make key table-driven suites parallel-safe. Also fixed flaky installer
test execution under repeated/parallel runs.
* chore: fix goimports ordering for golangci-lint
* Test(download): expand integration coverage for download paths
Add integration scenarios for force/pull repo updates, repo-only and skip semantics,
and direct AUR download/scanner coverage used by getpkgbuild and package preparation.
* Test(exe): relax systemd-run path assertion
Fix flaky TestBuildGitCmd by accepting an absolute systemd-run path while still
asserting the expected binary is used.
* Test(text): avoid race in color tests
Remove parallel execution from TestColorHash so global UseColor writes do not
overlap with color consumers in parallel tests and trigger race detector
failures.
* fix potential race conditions
