Feat/implement reputation storage

[devfoma]

Summary

This pr closes #84

• Formalized on-chain reputation by introducing a unified Profile storage structure per address.
• Optimized storage footprint by consolidating client and freelancer metrics into a single persistent ledger entry.
• Added support for decentralized metadata linking via metadata_hash (IPFS CID) for user bios and headlines.
• Refactored submit_rating, update_score, and slash methods to utilize the modularized profile and storage components.
• Maintained backward compatibility for the get_score public API while enabling future expansion of decentralized identity features.

Testing

• All existing reputation unit tests verified against the new unified storage model.
• New test case test_profile_metadata verified IPFS hash persistence and authorization.
• New test case test_unified_storage verified cross-role metric coexistence in a single address entry.

Checklist

• Linked issue or backlog item (Implement Reputation storage (per address))
• Contract behavior and invariants are described clearly
• Docs updated if contract interfaces or workflows changed
• Scope stays limited to one contract concern (Reputation storage)

[drips-wave]

@devfoma Great news! 🎉 Based on an automated assessment of this PR, the linked Wave issue(s) no longer count against your application limits.

You can now already apply to more issues while waiting for a review of this PR. Keep up the great work! 🚀

Learn more about application limits