feat: Implement advanced foil effects with rolling rainbow, circular glare, and mobile entrance animations, alongside a fix for foil rendering on non-foil cards.

docs/development/devlog/2025-12-17-015000_mild_foil_animation.md

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+# Mild Foil Animation
+
+## Objective
+Reduce the intensity of foil effects to make the static appearance identical to non-foil cards (as requested), while keeping the animation "mildly visible" rather than dominating.
+
+## Changes
+- Modified `FoilOverlay` in `src/client/src/components/CardPreview.tsx`:
+    - **Removed Static Gloss**: Deleted the `bg-white/5 mix-blend-screen` layer. This ensures the base brightness of foil cards matches the standard "Universal Gloss" shared with non-foils.
+    - **Softened Circular Glare**:
+        - Reduced the white intensity in the radial gradient from `0.5` to `0.25`.
+        - Reduced the layer opacity from `80` to `25`.
+        - This makes the rotating white sheen subtle and ghostly rather than a bright spotlight.
+    - *Retained*: The low-opacity rolling rainbow layer (`opacity-30`) to provide the necessary color play.
+
+## Result
+Foil cards now look cleaner and less washed out, matching the visual weight of normal cards, but possess a delicate, rotating shimmer that catches the eye without distracting from the art.