feat(core): add deterministic performance snapshots

[raymondjacobson]

Summary

• add versioned deterministic node performance scoring, allocations, protocol Merkle proofs, and shared Keccak helpers
• add a fail-closed finalized epoch manifest with registered source identity, finalized block binding, per-operator evidence, and stake-weighted useful-work consensus
• add the production-shaped performance-snapshot CLI for preparing/signing input consensus, generating immutable relayer artifacts, and signing the exact Solana snapshot commitment
• publish open, attest, finalize, and claim arguments plus per-operator proofs for relayers and dashboards
• add Go/Rust golden vectors, malformed-proof properties, strict JSON and persistence validation, and missing/non-consensus input tests

Invocation

• performance-snapshot prepare-input
• performance-snapshot sign-input
• performance-snapshot generate
• performance-snapshot sign-snapshot

See cmd/performance-snapshot/README.md for schemas, quorum collection, artifact consumption, and deployment environment variables.

Testing

• gofmt -d on all changed Go files
• golangci-lint v1.64.8 run --new-from-rev origin/main on the changed packages
• go test -race ./pkg/common ./pkg/core/performance ./cmd/performance-snapshot -count=1
• go vet ./pkg/common ./pkg/core/performance ./cmd/performance-snapshot
• go test ./pkg/core/... -count=1
• go test ./pkg/core/performance -run ^$ -fuzz ^FuzzMerkleProofProperties$ -fuzztime=5s
• go build ./cmd/performance-snapshot