Implement Scatterplot Zoom custom visualization

[google-labs-jules]

• Created new package packages/scatterplot-zoom.
• Implemented Looker Custom Viz using @visx library.
• Supports Pivoted data (multi-series) and Flat data.
• Supports Zoom/Pan interaction.
• Implemented Dark/Neon theme with configurable options.
• Added Tooltip support.
• Note: Integration tests were skipped due to persistent environment issues (zombie servers). Code verified via compilation.

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PR created automatically by Jules for task 2515209106167606864 started by @LukaFontanilla

[google-labs-jules]

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