[OPIK-5305] [FE] fix: show dashboard resize handle on hover only

[andriidudar]

Details

Hide the dashboard widget resize corner handle by default and only show it when hovering over the widget. Previously the resize grip (SVG icon from react-grid-layout) was always visible. Now it fades in with a 0.2s opacity transition on hover.

Change checklist

• User facing
• Documentation update

Issues

• OPIK-5305

AI-WATERMARK

AI-WATERMARK: yes

• If yes:
  • Tools: Claude Code
  • Model(s): Claude Opus 4.6
  • Scope: full implementation
  • Human verification: code review + manual testing

Testing

• Verified frontend lint, typecheck, and dependency validation pass (scripts/dev-runner.sh --lint-fe)
• Manual verification: navigate to a dashboard with widgets, confirm resize handle is hidden by default and appears on widget hover

Documentation

N/A

[github-actions]

🔄 Test environment deployment process has started

Phase 1: Deploying base version 1.10.56-4730 (from main branch) if environment doesn't exist
Phase 2: Building new images from PR branch andriidudar/OPIK-5305-resize-icon-hover-only
Phase 3: Will deploy newly built version after build completes

You can monitor the progress here.

[CometActions]

✅ Test environment is now available!

To configure additional Environment variables for your environment, run [Deploy Opik AdHoc Environment workflow] (https://github.com/comet-ml/comet-deployment/actions/workflows/deploy_opik_adhoc_env.yaml)

Access Information

• URL: https://pr-5971.dev.comet.com
• Cluster: comet-ml-development
• Namespace: pr-5971
• Version: 1.10.56-5971-merge-1737
• Application logs: View in Grafana

The deployment has completed successfully and the version has been verified.

[CometActions]

🌙 Nightly cleanup: The test environment for this PR (pr-5971) has been cleaned up to free cluster resources. PVCs are preserved — re-deploy to restore the environment.