🎨 Palette: Add active states to buttons and cards for tactile feedback

[keough99]

💡 What: Added :active states to .btn and .social-card elements.
🎯 Why: To provide satisfying, continuous tactile feedback during interactions, pairing with their existing transform-based hover states.
📸 Before/After: Visual changes verified via Playwright.
♿ Accessibility: Improves visual feedback during interaction.

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PR created automatically by Jules for task 3903767818597689309 started by @keough99

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