feat: the agent brings USDC from the owner's Unified Balance to pay invoices

[JaDi03]

• New agent tools: cash_position shows the owner's USDC on other chains; estimate_bring_funds and bring_funds move the split the model chooses to the owner's own wallet on Arc (never anywhere else), with fees and the transaction back to the model.
• Circle's Unified Balance Kit 1.8.0 runs in a small Node script (services/unified_balance/kit); at start the agent's Circle wallet gets the same address on each source chain.
• Dashboard: Settings > USDC on other chains, to deposit and authorize the agent per chain with the kit and its viem adapter (vendored bundle).
• install.sh adds Node 22 and pnpm; the CSP allows Circle Gateway and the kit's nodes for those chains; CI runs the kit's tests.