Tune mesh retry behavior and builds

examples/simple_secure_chat/main.cpp

@@ -202,6 +202,10 @@ protected:
     return true;
   }
 
+  uint8_t getDefaultTxCodingRate() const override {
+    return LORA_CR;
+  }
+
   void onDiscoveredContact(ContactInfo& contact, bool is_new, uint8_t path_len, const uint8_t* path) override {
     // TODO: if not in favs,  prompt to add as fav(?)