🎨 Palette: Add focus indicators and disabled states

[mapleleaflatte03]

💡 What

Added global :focus-visible outlines and visually distinct :disabled states to interactive elements (button, input, select, .cta, .operator-action) across the platform by updating the core CSS.

🎯 Why

Previously, interactive elements lacked clear visual indicators when focused via keyboard or when disabled. This made it difficult for users to determine which element was currently active or if an action was unavailable, leading to a confusing and less intuitive experience.

📸 Before/After

• Before: Focused elements had no visible outline, making keyboard navigation nearly impossible. Disabled buttons looked identical to active ones, providing no visual cue that they were inactive.
• After: Interactive elements now display a distinct 2px solid var(--accent) outline with an offset when focused via keyboard. Disabled elements show a reduced opacity (50%) and a not-allowed cursor to clearly indicate they cannot be interacted with.

♿ Accessibility

• Keyboard Navigation: Vastly improves keyboard navigation by ensuring all interactive elements have a clear, visible focus indicator (:focus-visible), allowing users to confidently navigate the app without a mouse.
• State Communication: Clearly communicates the "disabled" state of form controls and actionable buttons, preventing user frustration from clicking inactive elements.

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PR created automatically by Jules for task 17112741356535179532 started by @mapleleaflatte03

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