Agent0 Subgraphs index ERC-8004 agent activity

The Graph's Agent0 Subgraphs now index all on-chain activity generated by ERC-8004, which is live on five networks. Every agent registration, metadata update, and feedback entry emits on-chain events that Agent0 captures under a single GraphQL schema.

This lets an agent find and score a counterparty in a single query, instead of stitching together data across chains and formats.