feat: loading animation

[robertlinde]

This pull request introduces a user experience improvement to the tour component by visually indicating when the next step is being prepared and may take a moment to appear. Now, if a step transition is delayed (due to loading data, rendering, or other async operations), the tooltip dims and shows a progress cursor to signal that the tour is working, both on web and React Native. This prevents confusion where previously the UI appeared unresponsive. The change is documented, implemented across platforms, and tested.

User experience improvements:

• The tooltip now dims and shows a progress cursor when the next step is being prepared and takes longer than a short threshold, indicating that the tour is working. This applies to both built-in and custom tooltips, on web and React Native. [1] [2] [3] [4] [5] [6] [7]

Implementation details:

• Added isWaiting prop and related logic to TooltipFrame and its call sites, controlling the dimming effect and progress cursor. [1] [2] [3] [4] [5] [6] [7]
• Introduced new motion constants: waitingOpacity for the dimmed state and clarified waitingDimDelayMs for when the effect should start.

Documentation and testing:

• Updated CHANGELOG.md and README.md to describe the new behavior. [1] [2]
• Added a test to verify that the tooltip dims only when the next step takes a moment to prepare. [1] [2]