feat: wire retro-demoscene widgets into premium dashboard

[chernistry]

Summary

• Import and integrate 4 retro-demoscene widget modules (CRT shader, plasma canvas, tracker view, oscilloscope) into BernsteinApp dashboard
• Add uppercase keybindings (C/P/T/O) for toggling each widget, with a hidden #retro-bar container that auto-shows when any child is visible
• Feed live agent data to retro widgets from both the file watcher and HTTP poll paths
• Add CSS rules for the retro container and its children

Test plan

• uv run ruff format and uv run ruff check pass cleanly
• uv run pytest tests/unit/test_dashboard_retro_integration.py -x -q passes (2/2)
• Pre-push typecheck passes (0 errors)
• Manual: launch bernstein live, press C/P/T/O to toggle retro widgets

🤖 Generated with Claude Code

[github-actions]

AI Review (GitHub Models)

Summary

This pull request introduces several retro-demoscene widgets into the Bernstein dashboard, enhancing its visual functionality and interactivity. Key changes include the addition of new toggle actions for displaying various widgets and integration points for updating these widgets with agent data.

Risk Assessment

Medium - The modification incorporates new interactive elements which may introduce unforeseen complexities, particularly regarding display logic and state management of the retro widgets. Additionally, changes to the existing dashboard layout and user interactions could lead to usability issues if not thoroughly tested.

Actionable Recommendations

• Ensure comprehensive unit and integration tests cover all new functionality, especially the toggle actions and data updates for the retro widgets.
• Review and test the impact of adding new UI elements on the performance of the existing dashboard, particularly with high agent counts.
• Confirm that the new widgets do not cause any regressions in accessibility features or compatibility with existing user interfaces.
• Add documentation for the new features, including usage examples for the retro widgets and how users can interact with them.

[sonarqubecloud]

Quality Gate passed

Issues
7 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[github-actions]

CI Summary

Check	Result
Repo hygiene	✅ success
Lint	✅ success
Type check	✅ success
Tests	❌ failure
Spelling	✅ success
Dead code	✅ success
Workflow lint	✅ success
Dist size	✅ success
SonarCloud	⏭️ skipped

Coverage and detailed reports are available via Codecov and the Checks tab.