fix: browser_tests Phase 1 - mechanical fixes

- Rename dragAndDrop to dragDrop (7 occurrences)

- Add override modifiers in SidebarTab.ts (4 fixes)

- Remove .ts import extensions in actionbar.spec.ts

- Prefix unused variables with underscore (9 files)

- Fix ESLint import() type annotation in globals.d.ts

Reduces typecheck:browser errors from 229 to 215

Amp-Thread-ID: https://ampcode.com/threads/T-019c1787-c781-761d-b95a-4844e909e64c
Co-authored-by: Amp <amp@ampcode.com>

browser_tests/tests/menu.spec.ts

@@ -11,7 +11,7 @@ test.describe('Menu', { tag: '@ui' }, () => {
     const initialChildrenCount = await comfyPage.menu.buttons.count()
 
     await comfyPage.page.evaluate(async () => {
-      window.app.extensionManager.registerSidebarTab({
+      window.app!.extensionManager.registerSidebarTab({
         id: 'search',
         icon: 'pi pi-search',
         title: 'search',
@@ -155,7 +155,7 @@ test.describe('Menu', { tag: '@ui' }, () => {
 
     test('Can catch error when executing command', async ({ comfyPage }) => {
       await comfyPage.page.evaluate(() => {
-        window.app.registerExtension({
+        window.app!.registerExtension({
           name: 'TestExtension1',
           commands: [
             {