[Enhancement Request] - [Build specs overwriting and path sanitization overlaps due to incomplete purl/version handling]

Description

Currently, build specs are stored and retrieved partly based on the purl of the artifact but without the version component. As a result, running Macaron on different versions of the same artifact causes new results to overwrite previous results.

Additionally, the output path for build specs normalizes all special characters to underscores (_). This may cause path overlaps in cases where different meaningful characters are present in the artifact name, such as periods (.). For example, both foo.bar and foo_bar would map to foo_bar, causing collisions. The file naming strategy should preserve certain valid characters (such as .) and only sanitize those strictly necessary for file system safety, to avoid these issues.