feat(dashboard): add duplicate widget option

[okxint]

Summary

• Adds a Duplicate option to the chart dropdown menu (between Edit and Delete)
• Uses the existing POST /api/projects/:projectId/dashboard-charts endpoint to create a copy with the same query, config, and a " (copy)" suffix on the name
• New chart is placed at the default layout position (0,0) and existing charts are repositioned automatically by the backend

Changes

• chart-header.tsx: Accept full chart prop instead of just name/id, add Copy icon import, add handleDuplicateChart callback and "Duplicate" menu item
• chart.tsx: Pass chart object to ChartHeader

Closes #1498

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Note

Low Risk
Low risk UI change that adds a new dashboard action calling an existing create-chart endpoint; main risk is cache consistency/optimistic update behavior and handling of API failures.

Overview
Adds a Duplicate action to the dashboard chart header menu, creating a new chart via POST /api/projects/:projectId/dashboard-charts with the same query and settings.config and a " (copy)" name suffix, and updating the SWR cache (with revalidation) plus error toast on failure.

Refactors ChartHeader to accept the full chart object (instead of id/name) and updates chart.tsx to pass that object through.

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[CLAassistant]

All committers have signed the CLA.

[dinmukhamedm]

@okxint thanks for your contribution! Please do the following:

• pull the dev branch from upstream and start your branch from there (cleaner commit history)
• sign the CLA
• add a scheenshot of your changes

[cursor]

Cursor Bugbot has reviewed your changes and found 1 potential issue.

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[okxint]

Rebased onto the latest dev branch — commit history is now clean with just the 2 feature commits on top.

CLA is signed.

Will add a screenshot of the duplicate option in the dropdown menu shortly.