Enhancement: Add live mempool fee estimates to help users choose appropriate fee rates

[jan3-agent]

Description

The agent currently has no access to live Bitcoin mempool fee data. When executing transactions that require a fee rate (such as BTC sends or peg-ins), the agent cannot recommend an appropriate fee rate based on current network conditions. This can result in transactions sitting unconfirmed for hours if a low fee rate is used.

Proposed solution

Add a tool that fetches current fee estimates (slow, medium, fast) from mempool.space so the agent can make informed recommendations to the user.

Acceptance criteria

• Add mempool.space API integration to fetch current fee estimates
• Create a tool for querying fee estimates with slow/medium/fast options
• Tool returns accurate, real-time fee rates from the mempool
• Agent can recommend appropriate fee rates to users based on transaction priority

Notes

Priority: Medium — affects transaction timing but no funds at risk.