Add Uniswap V3 WebSocket swap price parsing

[kingzzoov-ctrl]

Summary

Adds concrete Uniswap V3 Swap-event parsing to the WebSocket price feed so issue #4 can turn eth_subscribe pool logs into live PricePoint updates instead of only accepting generic JSON price messages.

What changed

• Extended WebSocketConfig with optional asset metadata and token decimal/inversion settings for DEX pool pricing.
• Added UNISWAP_V3_SWAP_TOPIC and parser support for Ethereum log subscription payloads.
• Derives live pool price from sqrtPriceX96, adjusts for token decimal differences, and optionally inverts the pair direction.
• Updates _handle_message() to prefer Uniswap V3 Swap parsing before falling back to generic websocket price messages.
• Expanded tests for config generation, Swap-event decoding, ignored non-Swap logs, and cache updates from eth_subscription payloads.

Verification

.venv/bin/python -m pytest -q

Result: 95 passed, 2 skipped.

Closes #4

[abhicris]

🤖 Audit verdict: safe

Feature adds legitimate Uniswap V3 swap event parsing with correct event topic, proper decimal math (sqrtPriceX96 calculations), defensive input validation, no credential leakage, and well-tested implementation.

Audited by the kcolbchain PR pipeline. See pipeline docs.