gossip: log each option's label, so a row's meaning is readable

A count cannot say which row opens a shop, which is greyed, or which is
TurtleWoW's `CUSTOM_MERCHANT_TRIGGER` marker. The labels are the server's own
sentence; print them with the index, icon and coded flag beside each.

Verified: cargo clippy --workspace --all-targets -- -D warnings reports nothing
in this file. No test covers a debug! line.

crates/benilla-app/src/ui_gossip/net.rs

@@ -101,6 +101,17 @@ fn gossip_menu(
         options.len(),
         quests.len()
     );
+    // The labels, because a row's meaning is the server's sentence: a count cannot say which row
+    // opens a shop, which is greyed, or which is TurtleWoW's `CUSTOM_MERCHANT_TRIGGER` marker.
+    for opt in &options {
+        debug!(
+            "net:   option {} icon {} coded {} — {:?}",
+            opt.index,
+            opt.icon,
+            u8::from(opt.coded),
+            opt.message
+        );
+    }
     if gossip.open_menu(npc, text_id, options, quests, npc_gender) {
         let _ = net_commands
             .0