🎨 Palette: [UX improvement] Clear status bar state on error

[raccioly]

💡 What: The UX enhancement clears the statusBarItem.backgroundColor to undefined and updates statusBarItem.tooltip to provide contextual text when a JSON parse error or calculating exception occurs in the extension.

🎯 Why: The VS Code extension API persists the background color of status bar items across updates. If the score threshold drops below a passing limit, it sets a warning background color. If the next refresh hits an unknown error (e.g. unparseable JSON), the extension resets the text but the background color lingers, confusing users into thinking there is a warning state instead of an unknown error.

📸 Before/After: Visual change in the VS Code editor status bar (removes lingering warning/error colors when in error states, updates tooltip context).

♿ Accessibility: Ensures that status changes correctly reset their visual affordances so users depending on visual feedback (or screen reader tooltips) are not provided stale, inaccurate contexts.

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PR created automatically by Jules for task 579763078011676449 started by @raccioly

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