feat: RPC wave-4 benches 138-143 (Polygon zkEVM, Arbitrum Nova, X Layer, Flare, Core, Fuse)

[Flotapponnier]

Summary

• 6 new per-chain RPC latency bench pages (benches 138-143)
• Polygon zkEVM (1101): 3 providers — Polygon official, dRPC, Thirdweb
• Arbitrum Nova (42170): 3 providers — PublicNode, dRPC, Thirdweb
• X Layer (196): 3 providers — X Layer official, dRPC, Thirdweb
• Flare (14): 4 providers — Flare Foundation, dRPC, Thirdweb, Ankr
• Core Chain (1116): 4 providers — Core DAO, dRPC, Thirdweb, Ankr
• Fuse Network (122): 3 providers — Fuse Foundation, dRPC, Thirdweb
• config.go updated with 6 new Chain blocks for Railway RPC probes
• chains.ts, logo-manifest.ts, provider-registry.ts updated for all new chains
• All 6 chain logos added to public/logos/
• 118 specs valid, build clean