Record the SIP edge decision and align the docs:
- docs/adr/0001-sip-strategy.md: layered strategy (own Rust parser, rent the
interop tail via a Kamailio + rtpengine SBC, grow native core behind the shield);
pjproject FFI explicitly rejected for breaking the memory-safety thesis at the
most exposed seam.
- PORT_PLAN §1 + open decisions: SIP row updated to the decided strategy.
- ARCHITECTURE: "biggest technical risk" now points at ADR-0001.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01C2bfD7MkqEdfnMXxXBu456
