[tooling] anvil_fork.sh missing set -euo pipefail — failed commands silently continue, orphan anvil

[obchain]

Refs #52

File: scripts/anvil_fork.sh

Problem

Script lacks set -euo pipefail. A failed upstream probe or malformed anvil flag does not abort; later commands continue in undefined state. Anvil may boot with bad args, orphan its process, block port 8545 for the next run.

Fix

Add as first line after shebang:

#!/usr/bin/env bash
set -euo pipefail
IFS=$'\n\t'

Re-run shellcheck (shellcheck scripts/anvil_fork.sh) to catch other safety issues.

[obchain]

Already fixed at HEAD of feat/24-anvil-fork: set -euo pipefail present on line 27 of scripts/anvil_fork.sh.