test: add dual axis chart spec coverage

[cat0825]

What type of PR is this?

• test

What this PR does / why we need it

Adds unit coverage for getChartSpecWithContext when chartType is Dual Axis Chart.

The new test verifies that VMind's chart spec pipeline returns the expected VChart common spec, including the bar/line series, dual-axis field mapping, generated data values, and axis configuration.

Fixes #222

Which issue(s) this PR fixes

Fixes #222

Special notes for your reviewer

Validation run locally with Node 18.20.8:

• npx --yes node@18 ../../common/scripts/install-run-rush.js install
• npx --yes node@18 ../../common/scripts/install-run-rushx.js test -- --runTestsByPath __tests__/unit/getChartSpecWithContext_dualAxis.test.ts

I also ran npx --yes node@18 ../../common/scripts/install-run-rushx.js compile; it fails on pre-existing workspace type-resolution/type errors unrelated to this test-only change, mostly unresolved workspace package types such as @visactor/generate-vchart and @visactor/chart-advisor.

[cat0825]

Friendly follow-up on this dual-axis unit coverage. Related chart-type coverage for linear progress is in #297. Happy to adjust assertions if the expected common series shape has drifted.

[cat0825]

Friendly follow-up on this dual-axis unit coverage. Related chart-type coverage for linear progress is in #297. Happy to adjust assertions if the expected common series shape has drifted.

[cat0825]

Closing this from my side. The repository has had no commits since 2025-12-16 and no merged PRs since then, and this PR (plus #297 and #298) has been BLOCKED on maintainer approval for ~7 weeks with green CI, so there is no path to landing it right now.

Nothing is wrong with the coverage itself — the branch stays on my fork. If VMind maintenance resumes and you want the dual-axis / linear-progress / funnel spec coverage, reopen or ping me and I will rebase.