Implement chain data polling

[superposition]

Description

Poll Uniswap v4 pools and broadcast volatility updates.

Tasks

• Create chain polling service
• Connect to Ethereum RPC (configurable endpoint)
• Poll Uniswap v4 pool states periodically
• Generate volatility snapshots using @marigraph/chain
• Broadcast SURFACE_FULL on significant changes
• Broadcast SURFACE_DELTA for small changes
• Add configurable poll interval
• Handle RPC errors gracefully

Reference

• src/chain/volatility.ts - snapshot generation
• src/chain/uniswap.ts - pool state fetching

Acceptance Criteria

• Polls chain data at configured interval
• Broadcasts updates to connected clients
• Handles RPC failures without crashing

Labels

web-app, backend, server