Add diagnostic bit support to Gateway Modbus

- Introduced new enum value `kShortDiagnosticBit` to `GatewayModbusGeneratedKind`.
- Enhanced `GatewayModbusPoint` and `GatewayModbusPointBinding` structures to include diagnostic snapshot, boolean key, and device type.
- Added new diagnostic bit specifications and updated the corresponding arrays for generated discrete inputs and holding registers.
- Implemented `addGeneratedDiagnosticPoint` function to handle the creation of diagnostic points.
- Updated `rebuildMap` method to include generated diagnostic points during the map rebuilding process.

Co-authored-by: Copilot <copilot@github.com>

components/gateway_bacnet/include/gateway_bacnet.hpp

@@ -9,6 +9,7 @@
 
 #include <cstdint>
 #include <functional>
+#include <optional>
 #include <string>
 #include <vector>
 
@@ -32,6 +33,7 @@ struct GatewayBacnetObjectBinding {
   std::string property{"presentValue"};
   bool out_of_service{false};
   uint32_t reliability{0};
+  bool readable{false};
 };
 
 struct GatewayBacnetServerStatus {
@@ -46,13 +48,19 @@ using GatewayBacnetWriteCallback =
     std::function<bool(BridgeObjectType object_type, uint32_t object_instance,
                        const std::string& property, const DaliValue& value)>;
 
+using GatewayBacnetReadCallback =
+  std::function<std::optional<DaliValue>(BridgeObjectType object_type,
+                       uint32_t object_instance,
+                       const std::string& property)>;
+
 class GatewayBacnetServer {
  public:
   static GatewayBacnetServer& instance();
 
   esp_err_t registerChannel(uint8_t gateway_id, const GatewayBacnetServerConfig& config,
                             std::vector<GatewayBacnetObjectBinding> bindings,
-                            GatewayBacnetWriteCallback write_callback);
+                            GatewayBacnetWriteCallback write_callback,
+                            GatewayBacnetReadCallback read_callback = nullptr);
   GatewayBacnetServerStatus status() const;
   bool configCompatible(const GatewayBacnetServerConfig& config) const;
   bool handleWrite(BridgeObjectType object_type, uint32_t object_instance,
@@ -70,6 +78,7 @@ class GatewayBacnetServer {
 
   esp_err_t startStackLocked(const GatewayBacnetServerConfig& config);
   esp_err_t rebuildObjectsLocked();
+  void refreshPresentValues();
 
   static void TaskEntry(void* arg);
   void taskLoop();