feat: add L1 indexer to fetch contract logs for the bridge

[helciofranco]

Add L1 indexer, it'll sync contract events logs from a given start block number. After that, it'll keep watching the blockchain for new logs and blocks.

New env vars have been added to the graphql:

• FUEL_CHAIN_NAME (example fuelBeta5)
• ETH_CHAIN_NAME (example sepolia)
• ETH_ALCHEMY_ID (your alchemy key)
• ETH_INFURA_ID (your infura key – used as fallback to alchemy)
• ETH_INITIAL_BLOCK (block number that got our contracts)

📷 Indexer demo

pnpm sync:bridge

💾 API demo

Query	Result