add diag relay c++ bindings, screenshotr ffi (#58)

cpp/include/idevice++/diagnostics_relay.hpp

@@ -0,0 +1,60 @@
+// Jackson Coxson
+
+#pragma once
+#include <idevice++/bindings.hpp>
+#include <idevice++/ffi.hpp>
+#include <idevice++/provider.hpp>
+#include <idevice++/result.hpp>
+#include <string>
+#include <vector>
+
+namespace IdeviceFFI {
+
+using DiagnosticsRelayPtr =
+    std::unique_ptr<DiagnosticsRelayClientHandle,
+                    FnDeleter<DiagnosticsRelayClientHandle, diagnostics_relay_client_free>>;
+
+class DiagnosticsRelay {
+  public:
+    // Factory: connect via Provider
+    static Result<DiagnosticsRelay, FfiError> connect(Provider& provider);
+
+    // Factory: wrap an existing Idevice socket (consumes it on success)
+    static Result<DiagnosticsRelay, FfiError> from_socket(Idevice&& socket);
+
+    // API Methods - queries returning optional plist
+    Result<Option<plist_t>, FfiError>         ioregistry(Option<std::string> current_plane,
+                                                         Option<std::string> entry_name,
+                                                         Option<std::string> entry_class) const;
+
+    Result<Option<plist_t>, FfiError>         mobilegestalt(Option<std::vector<char*>> keys) const;
+
+    Result<Option<plist_t>, FfiError>         gasguage() const;
+    Result<Option<plist_t>, FfiError>         nand() const;
+    Result<Option<plist_t>, FfiError>         all() const;
+    Result<Option<plist_t>, FfiError>         wifi() const;
+
+    // API Methods - actions
+    Result<void, FfiError>                    restart();
+    Result<void, FfiError>                    shutdown();
+    Result<void, FfiError>                    sleep();
+    Result<void, FfiError>                    goodbye();
+
+    // RAII / moves
+    ~DiagnosticsRelay() noexcept                                     = default;
+    DiagnosticsRelay(DiagnosticsRelay&&) noexcept                    = default;
+    DiagnosticsRelay& operator=(DiagnosticsRelay&&) noexcept         = default;
+    DiagnosticsRelay(const DiagnosticsRelay&)                        = delete;
+    DiagnosticsRelay&             operator=(const DiagnosticsRelay&) = delete;
+
+    DiagnosticsRelayClientHandle* raw() const noexcept { return handle_.get(); }
+    static DiagnosticsRelay       adopt(DiagnosticsRelayClientHandle* h) noexcept {
+        return DiagnosticsRelay(h);
+    }
+
+  private:
+    explicit DiagnosticsRelay(DiagnosticsRelayClientHandle* h) noexcept : handle_(h) {}
+    DiagnosticsRelayPtr handle_{};
+};
+
+} // namespace IdeviceFFI