Implement Network Validator challenges and vector worker scoring end to end

[flo2517]

Implement the accepted Network Validator protocol so validators challenge Workers, verify results, submit weights, and update provider reputation through authorized finalized blockchain transitions. This is the only product-level validator role; Aura/GRANDPA participants are called Chain Authorities.

Acceptance criteria:

• Network Validators cannot score themselves or prohibited related Workers;
• randomized bounded challenges measure compute, storage, network/bandwidth, availability, and reliability;
• aggregate independent validator weights robustly and expose confidence/sample age;
• reputation vector contains compute, storage, network, availability, reliability, and global scores with checked integer arithmetic;
• invalid, late, replayed, copied, conflicting, or unavailable evidence is explicit and tested;
• governed rewards/penalties incentivize honest Workers and Network Validators;
• dashboard shows validator count, challenge outcomes, score history, and degraded quorum without false success.