Replaces the Go pia-wg-config (Go 1.23 rejects PIA legacy-CN no-SAN certs) with
PIA's official CA-pinned curl flow. Adds CA-aware region auto-pick so ExpressVPN-CA
migrated regions (e.g. us_chicago) auto-skip; region moved to us_denver. Tunnel
restored + egress verified 2026-06-30.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
tommy