feat(telemetry): highlight rows from graph hover

[mikemikimike]

Summary

• propagate graph-node hover state through the existing AppContext
• highlight matching telemetry step and insights rows by action name
• preserve the existing sequence-location hover behavior

Fixes #275

Validation

• npm ci --prefix telemetry/ui
• npm run build --prefix telemetry/ui — passed
• npm run test --prefix telemetry/ui -- --run — passed (1 test)
• targeted ESLint on the four changed files — passed
• git diff --check — passed

The full UI lint command on the Windows checkout reports existing repository-wide CRLF/Prettier errors in unrelated files; the changed files pass targeted ESLint validation.