feat(groove): add transport spec (IPv4/IPv6 dual-stack) and arXiv paper

spec/TRANSPORT.adoc — Transport layer requirements:
  - Dual-stack binding mandatory ([::]:PORT or both 127.0.0.1 + [::1])
  - IPv6-preferred probe order following RFC 8305 Happy Eyeballs
  - CORS headers mandatory for browser extension boundary
  - LAN discovery via mDNS/DNS-SD over IPv6 multicast (ff02::fb)
  - Data plane transport-agnostic (HTTP/WS/gRPC/WebRTC/Unix/BEAM)
  - Discovery scope: localhost default, LAN opt-in, WAN future

docs/groove-paper.tex — arXiv preprint draft:
  "Groove: Formally Verified System Composition via Dependent Types
   and Linear Resources"
  - Four formal safety theorems (match, linearity, authenticity, soundness)
  - Comparison table: Groove vs hard-coded/plugins/service-mesh
  - Reference implementation across Gossamer/Burble/VeriSimDB/Vext
  - FLI and browser extension harness described
  - Targets cs.SE/cs.PL, subsequently ICFP/POPL/ECOOP

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: hyperpolymath