feat(api-spec): drag-to-resize split pane with persisted width (#7866)

* Add drag-resize split pane for API Spec viewer

Introduce a drag-to-resize split pane for the API Spec viewer and persist left pane width. Adds a new useDragResize hook to manage dragging state and clamping, plus UI: dragbar styles, a loading state for the Swagger preview (onComplete + loader), and memoization of the Swagger renderer. Wire up persisted widths via Redux: add updateApiSpecPanelLeftPaneWidth (apiSpec slice) and updateApiSpecTabLeftPaneWidth (tabs slice), and propagate leftPaneWidth / onLeftPaneWidthChange through ApiSpecPanel, OpenAPISpecTab, RequestTabPanel and SpecViewer. Misc: pass tab uid into OpenAPISpecTab and add .gstack/ to .gitignore.

* Refactor SpecViewer and OpenAPISpecTab for improved loading and state management

- Updated SpecViewer to enhance loading state handling for Swagger content, ensuring a smoother user experience by preventing flashes of unrendered content.
- Refactored OpenAPISpecTab to streamline environment context management, optimizing the loading process for OpenAPI specifications.
- Simplified the useDragResize hook by removing unnecessary references and improving the handling of drag events, ensuring better performance and responsiveness during resizing actions.

* Enhance useDragResize hook to clamp width seed and improve test coverage

- Updated the useDragResize hook to clamp the width seed value, ensuring it stays within defined bounds during drag events.
- Added a new test case to verify that an out-of-bounds width seed is correctly clamped and persisted on immediate mouseup, enhancing the robustness of the drag-resize functionality.

* Remove .gstack/ from .gitignore

Delete the .gstack/ ignore entry and normalize the packages/bruno-converters/dist entry in .gitignore (deduplicated). No code changes; just tidy up ignore rules.

packages/bruno-app/src/components/RequestTabPanel/index.js

@@ -376,7 +376,7 @@ const RequestTabPanel = () => {
   }
 
   if (focusedTab.type === 'openapi-spec') {
-    return <OpenAPISpecTab collection={collection} />;
+    return <OpenAPISpecTab collection={collection} tabUid={focusedTab.uid} />;
   }
 
   if (!item || !item.uid) {