fix: data loss during network package deduplication

[Jaydeep869]

Description

Fixes #40

Network package deduplication in pkg/resolver/network/network.go was previously using a "first-wins" logic (map[string]struct{}). If a lightweight metadata trace was processed before a richer archive trace, later fields (like Hashes or DownloadURL) were being lost.

This PR replaces the deduplication method with a merge logic by mapping the PURL to the index in the original array. When duplicate PURLs are found, it intelligently merges missing metadata (e.g., DownloadURL, DownloadIP, Licenses, and Hashes) into the existing package entry.

Type of Change

• Bug fix (non-breaking change which fixes an issue)

Checklist:

• My code follows the style guidelines of this project
• I have performed a self review of my own code
• I have made corresponding changes to the documentation
• My changes generate no new warnings