Visualization management

[ivpusic]

Add visualization management support

[cursor]

PR Summary

Medium Risk
Extends the public DuneClient interface with new visualization methods, which is a potentially breaking API change for any external implementations. Otherwise changes are straightforward HTTP wrappers and new response/request models.

Overview
Adds full visualization management to the Go client beyond CreateVisualization: new GetVisualization, UpdateVisualization, DeleteVisualization, and ListQueryVisualizations methods and their corresponding /api/v1/visualization/:id and /api/v1/query/:id/visualizations endpoints.

Introduces new model types for visualization retrieval, update, delete, and paginated listing (GetVisualizationResponse, UpdateVisualizationRequest/Response, DeleteVisualizationResponse, ListVisualizationsResponse).

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