UI polish: update check tooltip date, expand/collapse icons, dialog JS

- NavMenu: show short date in update-check tooltip when last check was not today
- Settings modal: expand/collapse all sections with bi-arrows-expand/collapse icons
- Effective config: add Expand all button (bi-arrows-expand), same icon style as toolbar
- Rename settings-modal.js to dialog.js; add config-option-help.js, JS extension helpers
- Config option help modal and client settings/dialog wiring updates

src/DnsmasqWebUI/Extensions/JSRuntimeExtensions.cs

@@ -0,0 +1,56 @@
+using Microsoft.JSInterop;
+
+namespace DnsmasqWebUI.Extensions;
+
+/// <summary>
+/// Safe JS interop helpers that swallow disconnect/cancel/dispose exceptions.
+/// Use for best-effort or teardown calls; use raw InvokeVoidAsync/InvokeAsync when failure must propagate.
+/// </summary>
+public static class JSRuntimeExtensions
+{
+    /// <summary>
+    /// Invokes a void JS function without throwing on circuit disconnect, cancel, or dispose.
+    /// Returns true if the call succeeded, false otherwise.
+    /// </summary>
+    public static async ValueTask<bool> InvokeVoidAsyncSafe(
+        this IJSRuntime js,
+        string identifier,
+        CancellationToken cancellationToken = default,
+        params object?[]? args)
+    {
+        try
+        {
+            var a = args ?? [];
+            if (cancellationToken == default)
+                await js.InvokeVoidAsync(identifier, a);
+            else
+                await js.InvokeVoidAsync(identifier, cancellationToken, a);
+            return true;
+        }
+        catch (JSDisconnectedException) { return false; }
+        catch (TaskCanceledException) { return false; }
+        catch (ObjectDisposedException) { return false; }
+    }
+
+    /// <summary>
+    /// Invokes a JS function that returns a value, without throwing on circuit disconnect, cancel, or dispose.
+    /// Returns default when the call fails (e.g. circuit gone).
+    /// </summary>
+    public static async ValueTask<T?> InvokeAsyncSafe<T>(
+        this IJSRuntime js,
+        string identifier,
+        CancellationToken cancellationToken = default,
+        params object?[]? args)
+    {
+        try
+        {
+            var a = args ?? [];
+            if (cancellationToken == default)
+                return await js.InvokeAsync<T>(identifier, a);
+            return await js.InvokeAsync<T>(identifier, cancellationToken, a);
+        }
+        catch (JSDisconnectedException) { return default; }
+        catch (TaskCanceledException) { return default; }
+        catch (ObjectDisposedException) { return default; }
+    }
+}