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/2025-12-17-011500_enhanced_foils.md

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+# Enhanced Foil Effects
+
+## Objective
+Make the foil effect on cards "more visible and cooler" by introducing a multi-layered holographic overlay.
+
+## Changes
+- Modified `src/client/src/components/CardPreview.tsx`:
+    - Created a consistent `FoilOverlay` component used by both Mobile and Desktop previews.
+    - **Layer 1 (Base Holo)**: Swapped previous subtle gradients for a vibrant `amber-300` / `fuchsia-400` / `cyan-400` gradient with `mix-blend-color-dodge`. Increased opacity to `100` (blended mode handles the transparency feel).
+    - **Layer 2 (Shimmer)**: Added a diagonal white pulse (`animate-pulse`) with `mix-blend-overlay` to simulate catching the light.
+    - **Layer 3 (Depth)**: Added a top-down `white-to-black` gradient with `mix-blend-soft-light` to simulate metallic curvature/surface depth.
+    - Fixed linting errors from previous edits (syntax issues with spaces in class strings).
+
+## Result
+Foil cards now possess a distinct, colorful, and metallic sheen that animates, making them stand out significantly more than standard cards.