feat: handle AdminResult.RateLimited from SDK, update MeshTopology API

- Add AdminException.RateLimited to domain exception hierarchy
- Handle AdminResult.RateLimited in SdkRadioController.unwrap()
- Update MeshTopologyService for SDK's new suspend API:
  topology.nodes → topology.nodes(), topology.edgeCount → edgeCount()

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

core/data/src/commonMain/kotlin/org/meshtastic/core/data/radio/MeshTopologyService.kt

@@ -56,7 +56,7 @@ class MeshTopologyService {
         mutex.withLock {
             topology.addNeighborInfo(info)
             _edges.value = topology.allEdges()
-            _nodeCount.value = topology.nodes.size
+            _nodeCount.value = topology.nodes().size
         }
         Logger.d { "[Topology] Ingested neighbors from ${info.nodeId}: ${info.neighbors.size} edges" }
     }
@@ -66,7 +66,7 @@ class MeshTopologyService {
         mutex.withLock {
             topology.removeNode(nodeId)
             _edges.value = topology.allEdges()
-            _nodeCount.value = topology.nodes.size
+            _nodeCount.value = topology.nodes().size
         }
     }
 

core/data/src/commonMain/kotlin/org/meshtastic/core/data/radio/SdkRadioController.kt

@@ -405,6 +405,7 @@ class SdkRadioController(
         is AdminResult.Unauthorized -> throw AdminException.Unauthorized()
         is AdminResult.NodeUnreachable -> throw AdminException.NodeUnreachable()
         is AdminResult.SessionKeyExpired -> throw AdminException.SessionKeyExpired()
+        is AdminResult.RateLimited -> throw AdminException.RateLimited()
         is AdminResult.Failed -> throw AdminException.RoutingError(routingError.name)
     }
 }

core/model/src/commonMain/kotlin/org/meshtastic/core/model/AdminException.kt

@@ -39,4 +39,7 @@ sealed class AdminException(message: String) : Exception(message) {
 
     /** Device reported a routing error not covered by the other subtypes. */
     class RoutingError(val errorName: String) : AdminException("Routing error: $errorName")
+
+    /** Device rate-limited the request; back off before retrying. */
+    class RateLimited : AdminException("Rate limit exceeded")
 }