test: add Window type augmentation and standardize window access

- Add browser_tests/types/globals.d.ts with Window interface augmentation

- Add types for app, graph, LiteGraph, LGraphBadge and test globals

- Standardize window['prop'] to window.prop across 37 test files

- Update browser_tests/tsconfig.json to include new type definitions

Amp-Thread-ID: https://ampcode.com/threads/T-019c16b3-cc31-70ea-9727-a933cb0ee942
Co-authored-by: Amp <amp@ampcode.com>

browser_tests/tests/actionbar.spec.ts

@@ -49,7 +49,7 @@ test.describe('Actionbar', { tag: '@ui' }, () => {
     // Find and set the width on the latent node
     const triggerChange = async (value: number) => {
       return await comfyPage.page.evaluate((value) => {
-        const node = window['app'].graph._nodes.find(
+        const node = window.app.graph._nodes.find(
           (n) => n.type === 'EmptyLatentImage'
         )
         node.widgets[0].value = value