🎨 Palette: Add progressive feedback to character counter

[Sczitzo]

💡 What: Updated the alternative thought character counter to provide progressive visual feedback (orange at 80%, red at 90%) and added quiet, accessible status warnings for screen readers.
🎯 Why: A static character counter provides no urgency until the limit is hit, and attaching aria-live to the changing text spams screen reader users on every keystroke.
📸 Before/After: The counter now changes color dynamically. Screen readers receive two static, non-spammy warnings via role="status" elements when approaching and hitting the limit.
♿ Accessibility: Improved screen reader experience by conditionally rendering hidden role="status" messages at specific thresholds instead of announcing every keystroke change.

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PR created automatically by Jules for task 11242849674477690822 started by @Sczitzo

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