refactor: wire helpers into ComfyPage and update test usages

Phase 2 of ComfyPage refactor:

- Add ToastHelper, DragDropHelper, CommandHelper instances to ComfyPage

- Remove migrated methods from ComfyPage (command, toast, dragDrop, workflow, canvasOps, nodeOps methods)

- Update all test files to use new helper paths

- Keep visibleToasts as passthrough getter for backward compatibility

Amp-Thread-ID: https://ampcode.com/threads/T-019c1666-ed27-773c-976a-07cc805d7a6c
Co-authored-by: Amp <amp@ampcode.com>

browser_tests/tests/keybindings.spec.ts

@@ -10,7 +10,7 @@ test.describe('Keybindings', { tag: '@keyboard' }, () => {
   test('Should not trigger non-modifier keybinding when typing in input fields', async ({
     comfyPage
   }) => {
-    await comfyPage.registerKeybinding({ key: 'k' }, () => {
+    await comfyPage.command.registerKeybinding({ key: 'k' }, () => {
       window['TestCommand'] = true
     })
 
@@ -26,7 +26,7 @@ test.describe('Keybindings', { tag: '@keyboard' }, () => {
   test('Should not trigger modifier keybinding when typing in input fields', async ({
     comfyPage
   }) => {
-    await comfyPage.registerKeybinding({ key: 'k', ctrl: true }, () => {
+    await comfyPage.command.registerKeybinding({ key: 'k', ctrl: true }, () => {
       window['TestCommand'] = true
     })
 
@@ -43,7 +43,7 @@ test.describe('Keybindings', { tag: '@keyboard' }, () => {
   test('Should not trigger keybinding reserved by text input when typing in input fields', async ({
     comfyPage
   }) => {
-    await comfyPage.registerKeybinding({ key: 'Ctrl+v' }, () => {
+    await comfyPage.command.registerKeybinding({ key: 'Ctrl+v' }, () => {
       window['TestCommand'] = true
     })