[idd] project: organize source layout

Move cadence and pipeline declarations under capture, and move local
named-pipe handling under ipc.

Flatten display contexts and rename files after their contained classes.
Keep transport headers limited to transport contracts and capabilities.

Consolidate CSwapChainProcessor definitions so each source file matches
the class it implements.

idd/LGIdd/transport/DirectFrameBufferMemory.h

@@ -0,0 +1,34 @@
+/**
+ * Looking Glass
+ * Copyright © 2017-2026 The Looking Glass Authors
+ * https://looking-glass.io
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the Free
+ * Software Foundation; either version 2 of the License, or (at your option)
+ * any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc., 59
+ * Temple Place, Suite 330, Boston, MA 02111-1307 USA
+ */
+
+#pragma once
+
+#include <stddef.h>
+
+struct DirectFrameBufferMemory
+{
+  void   * address = nullptr;
+  size_t   size    = 0;
+
+  explicit operator bool() const
+  {
+    return address && size;
+  }
+};