feat: add pytest-ipywidgets bbox testing, remove playwright (#999)

## Summary
Add pytest-ipywidgets for browser-based bbox interaction testing and
remove Playwright/Vitest infrastructure.

## Changes
- Add `tests/ui/test_bbox_interaction.py` with complete bbox workflow
testing
- Add pytest-ipywidgets>=1.54.0 dependency 
- Remove all Playwright tests, configs, and dependencies
- Remove Vitest testing infrastructure
- Update GitHub Actions workflow to focus on build and lint

## Benefits
- Faster widget-level testing vs full E2E
- Better debugging with console access
- Simplified maintenance with single test file
- Same bbox interaction validation maintained

## Related Issues
- Fixes #524 - Automated widget testing
- Replaces #928 - Playwright CI testing

---------

Co-authored-by: Kyle Barron <[email protected]>

Author: vgeorge

.github/workflows/test-js.yml

@@ -1,4 +1,4 @@
-name: CI
+name: JavaScript Build and Lint
 
 on:
   push:
@@ -11,7 +11,7 @@ concurrency:
   cancel-in-progress: true
 
 jobs:
-  lint-and-test:
+  build-and-lint:
     runs-on: ubuntu-latest
 
     steps:
@@ -42,6 +42,3 @@ jobs:
 
       - name: Lint check
         run: npm run lint
-
-      - name: Test
-        run: npm run test

.github/workflows/test.yml

@@ -59,6 +59,10 @@ jobs:
         run: |
           npm run build
 
+      - name: Install Playwright browsers
+        run: |
+          uv run playwright install chromium
+
       - name: Run tests
         run: uv run pytest