flow: remote-node via mock fed-sx transport + 7 tests (Phase 4 begins)

(remote-node addr fn) runs a node on a federation peer. Transport is the fed-sx
boundary, mocked by a peer registry (flow-peer-register!); raises
flow-remote-unreachable / flow-remote-no-fn. Composes with sequence/suspend/retry.
Also fixes conformance.sh to load remote.sx before api.sx.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

lib/flow/conformance.sh

@@ -25,6 +25,7 @@ SUITES=(
   "control     flow-ctl-tests-run!       lib/flow/tests/control.sx"
   "suspend     flow-sus-tests-run!       lib/flow/tests/suspend.sx"
   "recovery    flow-rec-tests-run!       lib/flow/tests/recovery.sx"
+  "distributed flow-dist-tests-run!      lib/flow/tests/distributed.sx"
 )
 
 TMPFILE=$(mktemp); trap "rm -f $TMPFILE" EXIT
@@ -42,6 +43,7 @@ emit_eval () { echo "(epoch $EPOCH)"; echo "(eval \"$1\")"; EPOCH=$((EPOCH+1));
   emit_load "lib/scheme/runtime.sx"
   emit_load "lib/flow/spec.sx"
   emit_load "lib/flow/store.sx"
+  emit_load "lib/flow/remote.sx"
   emit_load "lib/flow/api.sx"
   for SUITE in "${SUITES[@]}"; do
     read -r _NAME _RUNNER FILE <<< "$SUITE"