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/graph.spec.ts

@@ -13,7 +13,7 @@ test.describe('Graph', { tag: ['@smoke', '@canvas'] }, () => {
     await comfyPage.workflow.loadWorkflow('inputs/input_order_swap')
     expect(
       await comfyPage.page.evaluate(() => {
-        return window.app.graph.links.get(1)?.target_slot
+        return window.app!.graph!.links.get(1)?.target_slot
       })
     ).toBe(1)
   })