Update sim evm defi-positions route to /v1/evm/defi/positions

[ivpusic]

Summary

• Point dune sim evm defi-positions at the stable /v1/evm/defi/positions/<address> route (was /beta/evm/defi/positions/<address>).
• Drop the "endpoint is in beta" note from the command's long help, since it's now v1.

Test plan

• go build ./...
• go test ./cmd/sim/...
• Live call: go run ./cmd sim evm defi-positions 0xd8da6bf26964af9d7eed9e03e53415d37aa96045 --chain-ids 1 returns the expected positions table and aggregation summary
• -o json output parses as expected (positions + aggregations)

[cursor]

PR Summary

Low Risk
Low risk CLI change that only updates the HTTP route and help text; main risk is unexpected behavioral differences between /beta and /v1 responses or availability.

Overview
Updates dune sim evm defi-positions to call the stable GET /v1/evm/defi/positions/<address> endpoint instead of the previous /beta/... route.

Removes the CLI help text note indicating the endpoint is beta, aligning command documentation with the new v1 API.

^{Reviewed by Cursor Bugbot for commit 69470fb. Configure here.}