🎨 Palette: [UX improvement] Add dynamic labels and disabled state tooltips to MenuBar buttons

[acebytes]

💡 What: Added dynamic labels ("Scanning...", "Running...") and .help() tooltips to the Rescan, Smart Clean, and Docker Prune buttons in the MenuBar popup.
🎯 Why: Users can feel confused when a primary button is disabled without explanation or lacks immediate inline text feedback during async operations.
📸 Before/After: Visual changes to button labels during scanning/cleaning states.
♿ Accessibility: Tooltips explain the disabled states (e.g., "No recoverable caches found"), aiding usability for all users.

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PR created automatically by Jules for task 1918037357832598756 started by @acebytes

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