feat: Migrate from ipywidgets to MIME renderer architecture (v0.4.0)

[terapyon]

PR Description

Overview

This PR implements a major migration from ipywidgets-based rendering to MIME renderer architecture (v0.4.0). This
change simplifies installation, improves compatibility with modern JupyterLab environments, and provides a
cleaner codebase.

Key Changes

Architecture Overhaul

• Complete removal of ipywidgets dependency: Migrated to MIME renderer using custom MIME type
  application/vnd.netvis+json
• Removed nbextension support: Optimized exclusively for JupyterLab 3.x/4.x (Jupyter Notebook Classic is no
  longer supported)
• Simplified installation: Manual extension enabling is no longer required

Implementation Improvements

Frontend (TypeScript)

• Added: src/mimePlugin.ts - Entry point for JupyterLab MIME extension
• Added: src/renderer.ts - MIME data rendering logic
• Refactored: src/graph.ts - D3.js visualization core logic (duplicate code removed)
• Removed: src/widget.ts, src/plugin.ts, src/extension.ts - ipywidgets-related code

Backend (Python)

• Updated: net_vis/netvis.py - MIME output support via _repr_mimebundle_()
• Removed: _jupyter_nbextension_paths() from net_vis/__init__.py
• Removed: net_vis/tests/test_nbextension_path.py - obsolete nbextension test

Enhanced Test Coverage

• TypeScript Tests: 41 tests implemented (Jest)
  • src/__tests__/mimePlugin.test.ts - MIME plugin unit tests (18 tests)
  • src/__tests__/renderer.test.ts - Renderer component tests (20 tests)
  • src/__tests__/graph.test.ts - Graph visualization logic tests (3 tests)
• Python Tests: All 16 tests passing (pytest)
  • MIME bundle structure validation
  • Version information embedding verification
  • Error handling validation

CI/CD Optimization

• GitHub Actions build.yml improvements:
  • Removed Yarn 4.6.0 pinning (now uses Yarn 1.22.x)
  • JavaScript tests and linting run only on Ubuntu (Windows/macOS run build verification only)
  • Reduced build time and cost
• Jest configuration improvements: Excluded /venv/ to suppress Haste warnings

Version Management and Frontend-Backend Communication

• Added version validation between frontend and backend
• Displays warnings when version mismatch is detected

Breaking Changes

❌ Removed Features

• ipywidgets support
• Jupyter Notebook Classic nbextension support
• _jupyter_nbextension_paths() function

✅ Maintained Compatibility

• Python API is 100% compatible: Existing code using NetVis(value=data) works without modification
• All D3.js visualization features preserved:
  • Force-directed layout
  • Node dragging, zoom, pan
  • Interactive tooltips
  • Custom node colors and sizes
  • Directed edges with arrows

System Requirements

• Supported: JupyterLab 3.x, 4.x
• Not Supported: Jupyter Notebook Classic
• Python: 3.10, 3.11, 3.12
• OS: Ubuntu, Windows, macOS
• D3.js: 7.9+

Documentation

• MIGRATION.md: Migration guide from 0.3.x to 0.4.0
• CHANGES.md: Detailed changelog
• README.md: Updated installation instructions

Test Results

✅ Python Tests

============================== 16 passed in 0.02s ==============================

✅ TypeScript Tests

Test Suites: 3 passed, 3 total
Tests: 41 passed, 41 total

✅ Lint

✨ Done in 2.35s

✅ Build

TypeScript compilation: Success

Related Issues

Closes #[issue_number] (if applicable)

Review Points

1. Validity of architecture change (ipywidgets → MIME renderer)
2. Backward compatibility (no changes to Python API)
3. Test coverage (41 TypeScript tests, 16 Python tests)
4. CI/CD optimization (Yarn version, OS-specific test strategy)
5. Documentation completeness (MIGRATION.md, CHANGES.md)

File Statistics

• 45 files changed: +9,603 additions, -9,744 deletions
• Major additions: MIME renderer architecture, comprehensive test suite, migration documentation
• Major deletions: ipywidgets code, nbextension support, obsolete tests