Fix property GUI updates by using ClientConnectionModel callbacks

Problem

The GUI property updates were not working for SetPropertyDataReply messages because InitiatorWidget::setupPropertyCallbacks() was bypassing the ClientConnectionModel callback system and registering directly with ObservablePropertyList. This meant that while the callback was invoked, it didn't trigger the proper GUI update chain.

Solution

Replaced direct ObservablePropertyList callbacks with ClientConnectionModel callbacks in InitiatorWidget to mirror the Kotlin implementation pattern:

Before (bypassing ClientConnectionModel):

observable_properties->addPropertyUpdatedCallback([this](const std::string& propertyId) {
    QMetaObject::invokeMethod(this, [this]() {
        updatePropertyList();
    }, Qt::QueuedConnection);
});

After (using ClientConnectionModel callbacks):

connection->add_properties_changed_callback([this]() {
    QMetaObject::invokeMethod(this, [this]() {
        updatePropertyList();
    }, Qt::QueuedConnection);
});

Key Insights from Kotlin Implementation

• Kotlin uses mutableStateListOf<PropertyValue>() for automatic Compose UI updates
• The critical callback conn.propertyClient.properties.valueUpdated.add { entry -> directly modifies the reactive state list
• Composable ClientPropertyList tracks vm.conn.properties directly for reactive updates
• Property details view uses vm.conn.properties.firstOrNull { it.id == propertyId } for reactive binding

The C++ version now replicates this reactive pattern by ensuring ClientConnectionModel callbacks properly trigger Qt widget updates.

Changes Made

• Modified InitiatorWidget::setupPropertyCallbacks() to use ClientConnectionModel callback system
• Removed direct ObservablePropertyList callback registration (19 lines removed, 5 lines added)
• Follows the same event dispatching chain as the Kotlin implementation
• Ensures SetPropertyDataReply messages trigger GUI updates via the proper callback chain

Testing

• ✅ Build completed successfully with no errors
• ✅ No other Qt widgets use the problematic direct callback pattern
• ✅ ClientConnectionModel.cpp properly calls registered callbacks in on_property_value_updated()
• ⚠️ GUI testing requires display environment (cannot test in headless environment)

Verification Steps

1. Build the application: cmake -B build && cmake --build build
2. Run the GUI application: ./build/tools/qt5-ci-tool/midicci-gui
3. Trigger property value updates (SetPropertyDataReply messages)
4. Verify that property values are displayed in the GUI interface
5. Confirm that property list updates correctly when properties change

Link to Devin run: https://app.devin.ai/sessions/69f0e6db929942fd921006ff78d5c946
Requested by: Atsushi Eno (atsushieno@gmail.com)