fix: use network config gas price for unls instead of hardcoded 0.0025

The hardcoded fallback was 10x lower than the chain's actual minimum
gas price (0.0025 vs 0.025), causing insufficient fee errors on IBC
transfers paid in NLS.

Author: kostovster

backend/src/refresh.rs

@@ -1214,10 +1214,14 @@ pub async fn refresh_gas_fee_config(state: &Arc<AppState>) {
         }
     }
 
-    // Always include unls as fallback (matching NolusWallet behavior)
-    gas_prices
-        .entry("unls".to_string())
-        .or_insert_with(|| "0.0025".to_string());
+    // Always include unls with gas price from network config (single source of truth)
+    if let Some(nolus) = gated.network_config.networks.get("NOLUS") {
+        let nls_price = nolus
+            .gas_price
+            .trim_end_matches(|c: char| c.is_alphabetic() || c == '_')
+            .to_string();
+        gas_prices.insert("unls".to_string(), nls_price);
+    }
 
     // Gas multiplier from gated network config for NOLUS (single source of truth)
     let gas_multiplier = gated