Add Roblox macOS forensic artifacts

[abrignoni]

Summary

• add 13 Roblox Desktop artifacts for macOS account, activity, logs, cookies, WebKit storage, IndexedDB, asset cache, and network cache data
• preserve raw credential-bearing values for evidentiary analysis
• document heuristic and format limitations in artifact notes

Validation

• focused Roblox profile against a real path-preserving ZIP corpus: 13 artifacts, 5,355 records, no parser errors
• CI-equivalent pylint: 10.00/10
• 26 local focused tests passed (test file intentionally not included because it is not required for artifact runtime)
• HTML, TSV, timeline, and LAVA output verified