Anonymize the client fixture as Project 2

[jerelvelarde]

Summary

• replace the client name with Project 2 across the synthetic Core fixture while preserving Account semantics
• reject every external fixture path lexically before filesystem access
• exercise provenance and expected topology directly in the golden contract
• seal all 44 fixture files plus the expectation artifact in the protocol 0.5 source inventory
• keep opaque synthetic IDs unchanged

Verification

• cargo fmt and strict Clippy pass
• folderbase-cli transform fixture: 24 passed
• folderbase-core template and root-attestation suites: 51 passed
• protocol 0.5 exact closure: 197 files, manifest sidecar verified
• tracked content and paths have no case-insensitive legacy client-name matches
• independent Spec review: GO
• independent Standards review: GO