Premium Analytics: Keep settings drawer above widget chrome in stories

[dognose24]

Fixes a Storybook-only stacking bug noticed while testing #50328.

Proposed changes

• Add isolation: isolate to the outer box of the shared WidgetDashboardWithWidget story helper. The widget settings drawer carries no z-index of its own (--wp-ui-drawer-z-index defaults to initial, per the @wordpress/ui Drawer contract), so dashboard-internal z-index: 1 elements (widget headers, resize handles) escalated to the document level and painted over the body-portaled drawer. Isolating the helper's stacking context keeps them contained — the same containment the wp-admin shell provides on the real dashboard, which is why the product surface was unaffected.

Related product discussion/links

Does this pull request change what data or activity we track or use?

No. Storybook story helper only; no runtime code is touched.

Testing instructions

• Run Storybook (pnpm run storybook:dev from projects/js-packages/storybook).
• Open any WidgetDashboardWithWidget story (e.g. Packages/Premium Analytics/Widgets/Locations or TopPlatforms).
• Click the widget's settings (⋯) trigger: the settings drawer should slide in above the widget, not behind its header.
• Confirm the wide-dashboard behavior still works: set a dashboardWidth wider than the preview and check the canvas scrolls horizontally while the drawer stays anchored to the viewport edge.

[github-actions]

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[jp-launch-control]

Code Coverage Summary

This PR did not change code coverage!

That could be good or bad, depending on the situation. Everything covered before, and still is? Great! Nothing was covered before? Not so great. 🤷

Full summary · PHP report

[dognose24]

🤖 Review-cycle summary — 6f30df3d

2 rounds; CI green; claude[bot] LGTM with no changes requested; no human comments pending.

Cycle detail

Commits added during the cycle: none — the initial commit passed review as-is.

Review outcome: claude[bot] independently verified the stacking analysis (drawer z-index initial vs widget chrome z-index: 1), endorsed isolation: isolate over forcing --wp-ui-drawer-z-index as the approach faithful to the product structure, and confirmed the wide-dashboard horizontal scroll behavior is unaffected.

CI: all required checks passing (mergeStateStatus: CLEAN).

[chihsuan]

Thanks for the fix!