[Logic] Add project metadata hash for on-chain verification

[AbelOsaretin]

Description

The URI field stores an off-chain pointer, but there's no on-chain proof of what the metadata contains. Adding a content hash would enable:

• Verification that metadata hasn't been tampered with
• On-chain proof of metadata existence
• Trustless metadata verification

Current Code Location

project_registry/src/types.rs:5-10 — ProjectData

Recommendation

• Add metadata_hash: BytesN<32> field to ProjectData
• Require hash to be provided during project creation
• Add verification function that compares hash against provided data

Severity

Low — Enhances trust and verification.