Add scripts for resolving and verifying Chromium binary paths

- Implemented `chrome-path.js` to define functions for locating Chromium binaries across different platforms and nested directories.
- Added `verify-chromium.js` to check for the presence of the Chromium binary and log the results, including candidate paths checked.
- The scripts support Linux, Windows, and macOS environments, enhancing the flexibility of Chromium binary detection.

src/StellaOps.Cli.Tests/Plugins/CliCommandModuleLoaderTests.cs

@@ -0,0 +1,41 @@
+using System;
+using System.CommandLine;
+using System.IO;
+using System.Threading;
+using Microsoft.Extensions.DependencyInjection;
+using Microsoft.Extensions.Logging.Abstractions;
+using StellaOps.Cli.Configuration;
+using StellaOps.Cli.Plugins;
+using Xunit;
+
+namespace StellaOps.Cli.Tests.Plugins;
+
+public sealed class CliCommandModuleLoaderTests
+{
+    [Fact]
+    public void RegisterModules_LoadsNonCoreCommandsFromPlugin()
+    {
+        var options = new StellaOpsCliOptions();
+        var repoRoot = Path.GetFullPath(
+            Path.Combine(AppContext.BaseDirectory, "..", "..", "..", "..", ".."));
+
+        options.Plugins.BaseDirectory = repoRoot;
+        options.Plugins.Directory = "plugins/cli";
+
+        var services = new ServiceCollection()
+            .AddSingleton(options)
+            .BuildServiceProvider();
+
+        var logger = NullLoggerFactory.Instance.CreateLogger<CliCommandModuleLoader>();
+        var loader = new CliCommandModuleLoader(services, options, logger);
+
+        var root = new RootCommand();
+        var verbose = new Option<bool>("--verbose");
+
+        loader.RegisterModules(root, verbose, CancellationToken.None);
+
+        Assert.Contains(root.Children, command => string.Equals(command.Name, "excititor", StringComparison.Ordinal));
+        Assert.Contains(root.Children, command => string.Equals(command.Name, "runtime", StringComparison.Ordinal));
+        Assert.Contains(root.Children, command => string.Equals(command.Name, "offline", StringComparison.Ordinal));
+    }
+}

src/StellaOps.Cli.Tests/Plugins/RestartOnlyCliPluginGuardTests.cs

@@ -0,0 +1,29 @@
+using StellaOps.Cli.Plugins;
+using Xunit;
+
+namespace StellaOps.Cli.Tests.Plugins;
+
+public sealed class RestartOnlyCliPluginGuardTests
+{
+    [Fact]
+    public void EnsureRegistrationAllowed_AllowsDuringStartup()
+    {
+        var guard = new RestartOnlyCliPluginGuard();
+        guard.EnsureRegistrationAllowed("./plugins/sample.dll");
+        guard.Seal();
+
+        // Re-registering known plug-ins after sealing should succeed.
+        guard.EnsureRegistrationAllowed("./plugins/sample.dll");
+        Assert.True(guard.IsSealed);
+        Assert.Single(guard.KnownPlugins);
+    }
+
+    [Fact]
+    public void EnsureRegistrationAllowed_ThrowsForUnknownAfterSeal()
+    {
+        var guard = new RestartOnlyCliPluginGuard();
+        guard.Seal();
+
+        Assert.Throws<InvalidOperationException>(() => guard.EnsureRegistrationAllowed("./plugins/new.dll"));
+    }
+}