refactor: change node count variables from uint8_t to uint16_t (#8478)

This is a non-breaking change that increases the internal representation
of node counts from uint8_t (max 255) to uint16_t (max 65535) to support
larger mesh networks, particularly on ESP32-S3 devices with PSRAM.

Changes:
- NodeStatus: numOnline, numTotal, lastNumTotal (uint8_t -> uint16_t)
- ProtobufModule: numOnlineNodes (uint8_t -> uint16_t)
- MapApplet: loop counters changed to size_t for consistency with getNumMeshNodes()
- NodeStatus: Fixed log format to use %u for unsigned integers

Note: Default class methods keep uint32_t for numOnlineNodes parameter
to match the public API and allow flexibility, even though internal node
counts use uint16_t (max 65535 nodes).

This change does NOT affect protobuf definitions, maintaining wire
compatibility with existing clients and devices.

src/graphics/niche/InkHUD/Applets/Bases/Map/MapApplet.cpp

@@ -287,7 +287,7 @@ void InkHUD::MapApplet::getMapCenter(float *lat, float *lng)
     float easternmost = lngCenter;
     float westernmost = lngCenter;
 
-    for (uint8_t i = 0; i < nodeDB->getNumMeshNodes(); i++) {
+    for (size_t i = 0; i < nodeDB->getNumMeshNodes(); i++) {
         meshtastic_NodeInfoLite *node = nodeDB->getMeshNodeByIndex(i);
 
         // Skip if no position
@@ -474,8 +474,8 @@ void InkHUD::MapApplet::drawLabeledMarker(meshtastic_NodeInfoLite *node)
 // Need at least two, to draw a sensible map
 bool InkHUD::MapApplet::enoughMarkers()
 {
-    uint8_t count = 0;
-    for (uint8_t i = 0; i < nodeDB->getNumMeshNodes(); i++) {
+    size_t count = 0;
+    for (size_t i = 0; i < nodeDB->getNumMeshNodes(); i++) {
         meshtastic_NodeInfoLite *node = nodeDB->getMeshNodeByIndex(i);
 
         // Count nodes