feat: make hover tooltip delay and search radius configurable

[ApurveKaranwal]

Resolves #177

Description

This PR addresses the intermittent hover tooltip behavior by exposing the internal tooltip and hit-detection constraints as configurable properties. The default values remain intact so this is fully backward compatible, but consumers can now override them for custom tooltip experiences (e.g., instant hover tooltips).

Changes Made

• Added tooltipDelay, tooltipRecentThreshold, and hoverRadius optional properties to the EmbeddingViewConfig interface.
• Updated the throttleTooltip utility to accept getter functions for delay and threshold timings, ensuring the reactive configuration state updates smoothly without needing to tear down the debouncer instance.
• Threaded the hoverRadius configuration down to queryClosestPoint in mosaic_client.ts to dynamically scale the nearest-neighbor hit detection.
• Added comprehensive unit tests in packages/viewer/test/utils.test.ts to verify the microtask and timer logic of throttleTooltip.

Testing

• npm run check passes successfully.
• Vitest suite in packages/viewer successfully passes (including 3 new timing-based unit tests for the updated tooltip debouncer logic).

[ApurveKaranwal]

@domoritz please tell me how to fix this issue? i think so CI Builds are not able to pass.

[domoritz]

You need to run the formatter. Read the error in https://github.com/apple/embedding-atlas/actions/runs/27203259746/job/80348187177#step:13:1

[ApurveKaranwal]

@domoritz sir, please check now, all the CI Builds have passed now, do let me know if i need to change anything in the PR.