chore: sync Electron smoke fix into v0.9.10

[numnx]

Summary

• sync the green dev integration state through PR fix: terminate Electron startup smoke reliably #3145 into release/v0.9.10
• preserve the release version at 0.9.10
• make the installed Electron readiness probe terminate deterministically on current macOS runners

Verification

• the release tree differs from dev only in package.json
• the sole difference is the intended version change from 0.9.9 to 0.9.10
• source PR fix: terminate Electron startup smoke reliably #3145 passed static checks, build, dependency audit, backend coverage, dashboard tests, package smoke, docs smoke, and Linux/macOS/Windows orchestration checks

Risk / rollback

The sync carries the already-green integration commit without additional source edits. Revert merge commit f56309602 if the release branch must return to its preceding candidate.