feat(adminui): B2-WP3 driver/device config modals + page-to-form refactor

Extract the 8 typed driver pages into embeddable <Driver>DriverForm bodies
(channel/protocol config) and add per-driver <Driver>DeviceForm bodies
(connection endpoint -> Device.DeviceConfig, v3 endpoint split). New
DriverConfigModal + DeviceModal dispatch by DriverType (DriverTypeNames) for
the /raw tree; Test-connect inside DeviceModal builds the merged Driver+Device
config transiently via DriverDeviceConfigMerger. Routed pages now host the
form bodies and keep working. Round-trip + enum-serialization guard tests for
the Modbus driver form + Modbus device model; retargeted the existing
page-form serialization tests + the _jsonOpts converter guard to the forms.

Claude-Session: https://claude.ai/code/session_01LVneM3eh1UtJxEisFXgmox

src/Server/ZB.MOM.WW.OtOpcUa.AdminUI/Components/Shared/Drivers/DeviceForms/GalaxyDeviceModel.cs

@@ -0,0 +1,29 @@
+using ZB.MOM.WW.OtOpcUa.AdminUI.Uns.TagEditors;
+
+namespace ZB.MOM.WW.OtOpcUa.AdminUI.Components.Shared.Drivers.DeviceForms;
+
+/// <summary>
+///     Device model for the AVEVA Galaxy driver. Galaxy connects to a SINGLE mxaccessgw gateway configured
+///     on the <b>driver</b> (nested Gateway/MxAccess records) — there is no flat per-device connection
+///     endpoint to author, so this model authors no endpoint keys. It simply round-trips the DeviceConfig
+///     JSON verbatim (preserving any keys) so the device row stays valid. (Flagged: Galaxy has no v3
+///     endpoint→DeviceConfig split; its connection lives on the driver config.)
+/// </summary>
+public sealed class GalaxyDeviceModel
+{
+    private System.Text.Json.Nodes.JsonObject _bag = new();
+
+    /// <summary>Loads a model from a DeviceConfig JSON string, retaining every original key.</summary>
+    /// <param name="json">The raw DeviceConfig JSON string, or null for a new/empty device.</param>
+    /// <returns>The populated <see cref="GalaxyDeviceModel"/>.</returns>
+    public static GalaxyDeviceModel FromJson(string? json)
+        => new() { _bag = TagConfigJson.ParseOrNew(json) };
+
+    /// <summary>Serializes the (preserved) DeviceConfig back to a JSON string.</summary>
+    /// <returns>The serialised DeviceConfig JSON string.</returns>
+    public string ToJson() => TagConfigJson.Serialize(_bag);
+
+    /// <summary>Validation hook; Galaxy device rows carry no endpoint, so always valid.</summary>
+    /// <returns><c>null</c> — no per-device endpoint to validate.</returns>
+    public string? Validate() => null;
+}