Fix tour styles

[Creylay]

Summary

Fixed several visual inconsistencies in the tour/tutorial system that appeared in light mode and across both themes. The main issues were: hardcoded dark backgrounds in tip boxes that broke in light mode, a spotlight border that was invisible or the wrong color in light mode due to incorrect handling of Joyride's mix-blend-mode: hard-light overlay, and an overly intense interactive step pulse animation.

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Type of Change

• Backend change
• Frontend change
• CI / Workflow change
• Build / Packaging change
• Bug fix
• Documentation

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Changes (by file)

• front/src/components/tour/TourProvider.jsx: Replaced hardLightInverse (computed only for dark backgrounds) with a mode-aware hlInverse(color, isDark) that correctly inverts the primary color through Joyride's mix-blend-mode: hard-light overlay — (255+x)/2 for dark pages, x/2 for light pages. Reduced pulse animation intensity and speed, and added a subtle glow to distinguish interactive steps from non-interactive ones in light mode.

• front/src/constants/tours/datasetsTour.js: Updated download button color from legacy orange (#ef9f27) to primary blue (#2C7AFF). Replaced hardcoded dark green tip boxes (#1b2f26, color: white) with semi-transparent green (rgba(76, 175, 80, 0.12), color: inherit) so they render correctly in both themes.

• front/src/constants/tours/notebookTour.js: Same tip box fix as datasetsTour.js.

• front/src/constants/tours/experimentsTour.js: Replaced light-only hardcoded backgrounds (#e3f2fd, #fff3e0, #f0f9ff) with semi-transparent equivalents. Added left border accents to match the tip box style used in other tours.

• front/src/constants/tours/modelsTour.js: Replaced dark-only text colors (#2e7d32, #d32f2f) with mid-brightness alternatives (#43A047, #e53935) readable on both light and dark dialog backgrounds. Changed color: #666 to color: inherit.

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Testing

• Verify the spotlight border appears in the correct primary blue in both light and dark mode.
• Check that tip boxes are readable across the datasets, notebook, experiments, and models tours in both themes.
• Confirm interactive steps have a subtle pulsing glow that distinguishes them from non-interactive steps in both modes.