Fix BusyBox grep incompatibility in containerized host IP detection

[Copilot]

The containerized gateway script fails when detecting host IP on Alpine Linux because it uses grep -oP (Perl regex), which BusyBox grep doesn't support.

Changes

run_containerized.sh:246 - Replace Perl regex with BusyBox-compatible pipeline:

# Before: Perl regex with lookbehind assertion (unsupported in BusyBox)
HOST_IP=$(ip -4 addr show 2>/dev/null | grep -oP '(?<=inet\s)\d+(\.\d+){3}' | grep -v '^127\.' | head -1)

# After: Standard POSIX commands
HOST_IP=$(ip -4 addr show 2>/dev/null | grep 'inet ' | awk '{print $2}' | cut -d/ -f1 | grep -v '^127\.' | head -1)

The new pipeline extracts the same IPv4 addresses using only commands available in BusyBox (grep, awk, cut).

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