enhancement(mesh): remove late packets from tx queue when full (#9779)

* enhance tx queue priority management

In busy environments, especially for ROUTER_LATE role, tx queue
fills very quickly. Delayed packets became late but new packets
to be retransmitted won't be put into the tx queue as old ones
stay there for a very long time (even a minute or more). This change
makes meshtastic prioritize new packets over late packets from tx queue
and allows to remove late packet from back of tx queue when there
is no space for a new one.

* apply copilot recommendation for cast

---------

Co-authored-by: Ben Meadors <benmmeadors@gmail.com>

src/mesh/MeshPacketQueue.cpp

@@ -184,6 +184,29 @@ bool MeshPacketQueue::replaceLowerPriorityPacket(meshtastic_MeshPacket *p)
         }
     }
 
+    if (backPacket->tx_after) {
+        // Check if there's a late packet at the queue end
+        auto now = millis();
+        if (backPacket->tx_after < now && (!p->tx_after || backPacket->tx_after > p->tx_after)) {
+            int32_t dt = (int32_t)(backPacket->tx_after - now);
+            if (p->tx_after) {
+                LOG_WARN("Dropping late packet 0x%08x with TX delay %dms to make room in the TX queue for packet 0x%08x with "
+                         "TX delay %ums",
+                         backPacket->id, dt, p->id, p->tx_after - now);
+
+            } else {
+                LOG_WARN("Dropping late packet 0x%08x with TX delay %dms to make room in the TX queue for packet 0x%08x "
+                         "with no TX delay",
+                         backPacket->id, dt, p->id);
+            }
+            queue.pop_back();
+            packetPool.release(backPacket);
+            // Insert the new packet in the correct order
+            enqueue(p);
+            return true;
+        }
+    }
+
     // If the back packet's priority is not lower, no replacement occurs
     return false;
 }