v0.14.1

fix(install): reuse existing config on upgrade, add --reconfigure flag

- On upgrade: automatically reads DNS_DOMAIN, NS_IP, MAXMIND_LICENSE_KEY,
  WEB_PORT, DNS_PORT, LOG_LEVEL from existing systemd service file
- Skip interactive prompts when values already configured
- Add --reconfigure / --force / -f flag to force re-entering all values
- Show old values as defaults when re-configuring (press Enter to keep)
- Mask MAXMIND_LICENSE_KEY display as '***' when reusing
- Add cap_net_raw capability for ICMP traceroute
- Show config summary after installation

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>