test(xmtp_mls,xmtp_api_d14n): bidi delivery fuzz — racing clients + proptest ledger model

Two layers of randomized no-loss checking for XIP-83 bidi delivery:

- Live fuzz against the containerized node: up to 10 racing member
  producers x up to 10 consumers (raw connections in the server-contract
  test; per-consumer proxied BidiTransports in the transport test), with
  per-lease strictly-increasing delivery, chain-union completeness, and
  toxiproxy network faults. Seeded and replayable; schedule telemetry
  proves every lever fires.
- Deterministic proptest model of the transport ledger over the scripted
  mock wire: generated op schedules (publish/lease/drop/serve/partial-
  serve/wire-kill) against an in-memory XIP-83 server model, with real
  shrinking. Found the virgin-topic snapshot loss and the cross-wave
  watermark gap-jump fixed in the tags commit; regression seeds checked in.

Author: tylerhawkes

.config/nextest.toml

@@ -42,3 +42,13 @@ path = "junit.xml"
 platform = 'cfg(all(target_family = "wasm", target_os = "unknown"))'
 default-filter = "not (test(/\\w*commit_log*/))"
 threads-required = 2
+
+# Fuzz tests print their seed and must fail loudly — a retry would re-roll
+# the seed and mask the finding.
+[[profile.default.overrides]]
+filter = 'test(/bidi_fuzz/)'
+retries = 0
+
+[[profile.ci.overrides]]
+filter = 'test(/bidi_fuzz/)'
+retries = 0