fix(packages): verify exact APK version

[jmgilman]

Summary

• replace the obsolete apk info -v output comparison with apk’s exact installed-version constraint
• preserve exact-version verification without relying on human-readable output

Verification

• go test ./internal/adapter/pkginstall ./internal/stage/pkgrepo ./internal/cli
• focused golangci-lint returned 0 issues
• Docker smoke check accepted release-cli=0.1.9 and rejected release-cli=0.1.8
• production replay proved APT and RPM installation, signed both APK indexes, then failed at the old assertion