feat(marmot-interop): patch wnd to honour \$WHITENOISE_DISCOVERY_RELAYS

Without this, wnd exits on startup with NoRelayConnections in any
environment that can't reach wnd's baked-in public discovery relay
set (nos.lol, relay.damus.io, …). The headless harness runs entirely
on a loopback relay, so hitting the public internet is never OK.

Changes:
- headless/patches/whitenoise-discovery-env.patch: adds an env-var
  override at the top of DiscoveryPlaneConfig::curated_default_relays.
  When \$WHITENOISE_DISCOVERY_RELAYS is set (comma-separated) we use
  that list instead of the hardcoded public one.
- headless/setup.sh: applies the patch in preflight (idempotent —
  checks for a .headless-discovery-patched marker), invalidates the
  previous wn/wnd build on first patch, rebuilds, and threads
  \$WHITENOISE_DISCOVERY_RELAYS=\$RELAY_URL into every start_daemon
  invocation.

https://claude.ai/code/session_01M6dCKAF5Y1VyHGZPjzwDXq

tools/marmot-interop/headless/patches/whitenoise-discovery-env.patch

@@ -0,0 +1,23 @@
+--- a/src/relay_control/discovery.rs
++++ b/src/relay_control/discovery.rs
+@@ -87,6 +87,20 @@
+
+     /// Initial curated relay set from the planning doc.
+     pub(crate) fn curated_default_relays() -> Vec<RelayUrl> {
++        // marmot-interop-headless patch: honour $WHITENOISE_DISCOVERY_RELAYS
++        // (comma-separated list) when present, so the harness can force wnd
++        // to use a loopback relay instead of the baked-in public set.
++        if let Ok(from_env) = std::env::var("WHITENOISE_DISCOVERY_RELAYS") {
++            let parsed: Vec<RelayUrl> = from_env
++                .split(',')
++                .map(str::trim)
++                .filter(|s| !s.is_empty())
++                .filter_map(|u| RelayUrl::parse(u).ok())
++                .collect();
++            if !parsed.is_empty() {
++                return parsed;
++            }
++        }
+         [
+             "wss://index.hzrd149.com",
+             "wss://indexer.coracle.social",

tools/marmot-interop/headless/setup.sh

@@ -30,16 +30,34 @@ preflight() {
   info "amy: $AMY_BIN"
 
   # Clone/build whitenoise-rs if needed (shared between both harnesses).
+  if [[ ! -d "$WN_REPO/.git" ]]; then
+    if [[ "$NO_BUILD" -eq 1 ]]; then
+      fail_msg "whitenoise-rs checkout missing at $WN_REPO and --no-build set"; exit 1
+    fi
+    step "cloning whitenoise-rs into $WN_REPO"
+    git clone --depth 1 https://github.com/marmot-protocol/whitenoise-rs.git "$WN_REPO" \
+      2>&1 | tee -a "$LOG_FILE"
+  fi
+
+  # Patch wnd's hardcoded discovery relays so $WHITENOISE_DISCOVERY_RELAYS
+  # wins — without this the daemon exits immediately in sandboxes / offline
+  # environments where public relays are unreachable.
+  local patch_file="$SCRIPT_DIR/headless/patches/whitenoise-discovery-env.patch"
+  local patch_marker="$WN_REPO/.headless-discovery-patched"
+  if [[ ! -f "$patch_marker" ]]; then
+    step "patching whitenoise-rs: honour WHITENOISE_DISCOVERY_RELAYS"
+    ( cd "$WN_REPO" && patch -p1 --forward --reject-file=- <"$patch_file" ) \
+      2>&1 | tee -a "$LOG_FILE"
+    touch "$patch_marker"
+    # Invalidate the previous build so the patched source is picked up.
+    rm -f "$WN_BIN" "$WND_BIN"
+  fi
+
   if [[ ! -x "$WN_BIN" || ! -x "$WND_BIN" ]]; then
     if [[ "$NO_BUILD" -eq 1 ]]; then
       fail_msg "wn/wnd not found and --no-build set"; exit 1
     fi
-    if [[ ! -d "$WN_REPO/.git" ]]; then
+    step "building wn + wnd (~5 min first run; incremental thereafter)"
-      step "cloning whitenoise-rs into $WN_REPO"
-      git clone --depth 1 https://github.com/marmot-protocol/whitenoise-rs.git "$WN_REPO" \
-        2>&1 | tee -a "$LOG_FILE"
-    fi
-    step "building wn + wnd (~5 min first run)"
     ( cd "$WN_REPO" && cargo build --release --features cli --bin wn --bin wnd ) \
       2>&1 | tee -a "$LOG_FILE"
   fi
@@ -143,8 +161,12 @@ start_daemon() {
   fi
   rm -f "$socket"
   mkdir -p "$data_dir/logs" "$data_dir/release"
-  nohup "$WND_BIN" --data-dir "$data_dir" --logs-dir "$data_dir/logs" \
+  # Point wnd's discovery plane at our loopback relay. Needs the env-var
-    >"$data_dir/logs/stdout.log" 2>"$data_dir/logs/stderr.log" &
+  # patch applied in preflight to take effect; without it wnd falls back
+  # to the baked-in public set and exits with NoRelayConnections.
+  WHITENOISE_DISCOVERY_RELAYS="$RELAY_URL" \
+    nohup "$WND_BIN" --data-dir "$data_dir" --logs-dir "$data_dir/logs" \
+      >"$data_dir/logs/stdout.log" 2>"$data_dir/logs/stderr.log" &
   echo "$!" > "$data_dir/pid"
   local deadline=$(( $(date +%s) + 30 ))
   while [[ $(date +%s) -lt $deadline ]]; do