feat(groove): add Paper 5 — The Exceptional Protocols

"The Exceptional Protocols: What We Thought Was Impossible,
 What Actually Was, and an Open Challenge"

Fifth paper. The scorecard paper. Seven things we said couldn't be
done, and the journey of discovering five of them could.

The Seven Exceptions:
  1. Open Internet (WAN)       → SOLVED: typed overlay (shared ABI)
  2. Encrypted Tunnels         → SOLVED: TLS ALPN negotiation
  3. Broadcast Protocols       → SOLVED: Typed Broadcast Filter
  4. IPv4→IPv6 Translation     → SOLVED: frame-level splice (verified)
  5. Browser↔Native            → SOLVED: Groove Browser Harness
  6. Hardware Bypass (RDMA)    → OPEN: DPDK/SmartNIC/XDP speculative
  7. Unknown Strangers         → IMPOSSIBLE: information-theoretic limit

Key insight: "The impossibility was an artefact of how we defined the
problem, not a property of the problem itself."

Open challenge to community: validate GRV6 type hash at line rate on
hardware-accelerated data path, <100ns per packet.

Update commitment: paper will be extended (not revised) when progress
is made on Exception 6.

Score: 5/7 solved. The untypeable residue is far narrower than expected.

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

Author: hyperpolymath