Phase 0 — mechanical rename ZB.MOM.WW.LmxOpcUa.* → ZB.MOM.WW.OtOpcUa.*

Renames all 11 projects (5 src + 6 tests), the .slnx solution file, all source-file namespaces, all axaml namespace references, and all v1 documentation references in CLAUDE.md and docs/*.md (excluding docs/v2/ which is already in OtOpcUa form). Also updates the TopShelf service registration name from "LmxOpcUa" to "OtOpcUa" per Phase 0 Task 0.6.

Preserves runtime identifiers per Phase 0 Out-of-Scope rules to avoid breaking v1/v2 client trust during coexistence: OPC UA `ApplicationUri` defaults (`urn:{GalaxyName}:LmxOpcUa`), server `EndpointPath` (`/LmxOpcUa`), `ServerName` default (feeds cert subject CN), `MxAccessConfiguration.ClientName` default (defensive — stays "LmxOpcUa" for MxAccess audit-trail consistency), client OPC UA identifiers (`ApplicationName = "LmxOpcUaClient"`, `ApplicationUri = "urn:localhost:LmxOpcUaClient"`, cert directory `%LocalAppData%\LmxOpcUaClient\pki\`), and the `LmxOpcUaServer` class name (class rename out of Phase 0 scope per Task 0.5 sed pattern; happens in Phase 1 alongside `LmxNodeManager → GenericDriverNodeManager` Core extraction). 23 LmxOpcUa references retained, all enumerated and justified in `docs/v2/implementation/exit-gate-phase-0.md`.

Build clean: 0 errors, 30 warnings (lower than baseline 167). Tests at strict improvement over baseline: 821 passing / 1 failing vs baseline 820 / 2 (one flaky pre-existing failure passed this run; the other still fails — both pre-existing and unrelated to the rename). `Client.UI.Tests`, `Historian.Aveva.Tests`, `Client.Shared.Tests`, `IntegrationTests` all match baseline exactly. Exit gate compliance results recorded in `docs/v2/implementation/exit-gate-phase-0.md` with all 7 checks PASS or DEFERRED-to-PR-review (#7 service install verification needs Windows service permissions on the reviewer's box).

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/ZB.MOM.WW.OtOpcUa.Client.UI/Services/JsonSettingsService.cs

@@ -0,0 +1,50 @@
+using System.Text.Json;
+
+namespace ZB.MOM.WW.OtOpcUa.Client.UI.Services;
+
+/// <summary>
+/// Persists user settings to a JSON file under LocalApplicationData.
+/// </summary>
+public sealed class JsonSettingsService : ISettingsService
+{
+    private static readonly string SettingsDir = Path.Combine(
+        Environment.GetFolderPath(Environment.SpecialFolder.LocalApplicationData),
+        "LmxOpcUaClient");
+
+    private static readonly string SettingsPath = Path.Combine(SettingsDir, "settings.json");
+
+    private static readonly JsonSerializerOptions JsonOptions = new()
+    {
+        WriteIndented = true
+    };
+
+    public UserSettings Load()
+    {
+        try
+        {
+            if (!File.Exists(SettingsPath))
+                return new UserSettings();
+
+            var json = File.ReadAllText(SettingsPath);
+            return JsonSerializer.Deserialize<UserSettings>(json, JsonOptions) ?? new UserSettings();
+        }
+        catch
+        {
+            return new UserSettings();
+        }
+    }
+
+    public void Save(UserSettings settings)
+    {
+        try
+        {
+            Directory.CreateDirectory(SettingsDir);
+            var json = JsonSerializer.Serialize(settings, JsonOptions);
+            File.WriteAllText(SettingsPath, json);
+        }
+        catch
+        {
+            // Best-effort save; don't crash the app
+        }
+    }
+}