Refactor and document: fix cert filenames, add Doxygen, improve demo

Refactoring (issues 1,3,4,5,7,8,9,10 from review):
- Replace hardcoded cert filenames with certFile/keyFile properties
- Add 30s timeout to certificate trust QEventLoop
- Cache servers() QVariantList instead of rebuilding per call
- Validate URLs before passing to QtOpcUa
- Use ComboBox valueRole for robust enum mapping
- Add certificate trust dialog to demo
- Remove unnecessary RowLayout wrapper
- Remove debug output from BuildDeps.cmake

Documentation:
- Add Doxygen file blocks to all C++ files
- Document AuthMode enum, toAuthenticationInformation(), key
  Q_INVOKABLE methods, certificateTrustRequested signal contract
- Convert section banners to standard format
- Add file/target comments to CMake and QML files

1 files changed, 5 insertions, 0 deletions

diff --git a/demo/main.cpp b/demo/main.cpp
index de3c2fc..b52df9e 100644
--- a/demo/main.cpp
+++ b/demo/main.cpp
@@ -1,8 +1,13 @@
+/**
+ * @file   main.cpp
+ * @brief  Entry point for the Bobink demo application.
+ */
 #include <QGuiApplication>
 #include <QQmlApplicationEngine>
 
 int main(int argc, char *argv[])
 {
+    // Load the locally-built OpcUa backend plugin (open62541).
     QCoreApplication::addLibraryPath(QStringLiteral(QTOPCUA_PLUGIN_PATH));
 
     QGuiApplication app(argc, argv);