feat: register the open demo vault command

Add the shared OpenDemoVaultCommandHandler to the command batch so users can open
the plugin's demo vault. The plugin test seeds the plugin notice component and
asserts the handler is constructed.

src/plugin.test.ts

@@ -3,9 +3,11 @@ import type {
   PluginManifest
 } from 'obsidian';
 import type { CommandHandlerComponent } from 'obsidian-dev-utils/obsidian/command-handlers/command-handler-component';
+import type { PluginNoticeComponent } from 'obsidian-dev-utils/obsidian/components/plugin-notice-component';
 
 import { Component } from 'obsidian';
 import { castTo } from 'obsidian-dev-utils/object-utils';
+import { OpenDemoVaultCommandHandler } from 'obsidian-dev-utils/obsidian/command-handlers/open-demo-vault-command-handler';
 import { PluginSettingsTabComponent } from 'obsidian-dev-utils/obsidian/components/plugin-settings-tab-component';
 import { strictProxy } from 'obsidian-dev-utils/strict-proxy';
 import { App } from 'obsidian-test-mocks/obsidian';
@@ -35,6 +37,10 @@ vi.mock('obsidian-dev-utils/obsidian/components/plugin-settings-tab-component',
 
 // --- Collaborator dev-utils components NOT added as children: bare constructor spies. ---
 
+vi.mock('obsidian-dev-utils/obsidian/command-handlers/open-demo-vault-command-handler', () => ({
+  OpenDemoVaultCommandHandler: vi.fn()
+}));
+
 vi.mock('obsidian-dev-utils/obsidian/command-handlers/open-settings-command-handler', () => ({
   OpenSettingsCommandHandler: vi.fn()
 }));
@@ -102,6 +108,7 @@ import { Plugin } from './plugin.ts';
 
 interface PluginInternals {
   _commandHandlerComponent: CommandHandlerComponent;
+  _pluginNoticeComponent: PluginNoticeComponent;
   onloadImpl(): void;
 }
 
@@ -128,6 +135,8 @@ describe('Plugin', () => {
     const registerCommandHandlers = vi.fn();
     // The base PluginBase.onload seeds and pre-wires commandHandlerComponent before onloadImpl; seed it here so onloadImpl can register the plugin's command handlers on it.
     internals._commandHandlerComponent = strictProxy<CommandHandlerComponent>({ registerCommandHandlers });
+    // The base PluginBase.onload also seeds pluginNoticeComponent before onloadImpl; seed it here so the OpenDemoVaultCommandHandler can read it via the non-null getter.
+    internals._pluginNoticeComponent = strictProxy<PluginNoticeComponent>({});
 
     internals.onloadImpl();
 
@@ -137,6 +146,7 @@ describe('Plugin', () => {
     expect(PluginSettingsTab).toHaveBeenCalledOnce();
     expect(DevToolsComponent).toHaveBeenCalledOnce();
     expect(registerCommandHandlers).toHaveBeenCalledOnce();
+    expect(OpenDemoVaultCommandHandler).toHaveBeenCalledOnce();
     expect(LongRunningTasksComponent).toHaveBeenCalledOnce();
     expect(ErrorStackTraceLimitComponent).toHaveBeenCalledOnce();
     expect(LongStackTracesComponent).toHaveBeenCalledOnce();

src/plugin.ts

@@ -1,6 +1,7 @@
 import type { FileSystemAdapter } from 'obsidian';
 
 import { getDebugController } from 'obsidian-dev-utils/debug';
+import { OpenDemoVaultCommandHandler } from 'obsidian-dev-utils/obsidian/command-handlers/open-demo-vault-command-handler';
 import { OpenSettingsCommandHandler } from 'obsidian-dev-utils/obsidian/command-handlers/open-settings-command-handler';
 import { PluginSettingsTabComponent } from 'obsidian-dev-utils/obsidian/components/plugin-settings-tab-component';
 import { PluginDataHandler } from 'obsidian-dev-utils/obsidian/data-handler';
@@ -46,7 +47,13 @@ export class Plugin extends PluginBase {
         app: this.app,
         settingTab: pluginSettingsTab
       }),
-      new ToggleDevToolsButtonCommandHandler(devToolsComponent)
+      new ToggleDevToolsButtonCommandHandler(devToolsComponent),
+      new OpenDemoVaultCommandHandler({
+        app: this.app,
+        pluginId: this.manifest.id,
+        pluginNoticeComponent: this.pluginNoticeComponent,
+        pluginVersion: this.manifest.version
+      })
     ]);
 
     new LongRunningTasksComponent({