fix(dashboard): validate imported widget config shape

[TINEROW]

Description

importWidgetConfig in src/app/hooks/useDashboardWidgets.tsx previously accepted any value where config.widgets was an array, then stored the raw entries into state and localStorage. Malformed entries (missing type/size/position, etc.) flowed into DashboardGrid and could crash the dashboard on next load since the layout is persisted.

This PR validates each imported widget against the Widget shape using a zod schema (widgetSchema / widgetListSchema) before accepting the import. Invalid configs are rejected, logged, and left out of state/persisted layout. Unit tests cover valid imports, malformed entries, and non-array configs.

Related Issue

Closes #939

Type of Change

• Bug fix
• New feature
• Breaking change
• Documentation update

Checklist

• Code follows project style guidelines
• Self-review completed
• No console errors
• Uses Lucide icons consistently
• Responsive design implemented
• Starknet best practices followed

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[RUKAYAT-CODER]

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