🎨 Palette: [Add mnemonics to animation controller panel]

[awest813]

• 💡 What: Added keyboard mnemonics (shortcuts) to the AnimationControllerPanel in the desktop editor. Users can now press Alt+P for Play, Alt+D for Default Loop, Alt+A for Always Loop, and Alt+N for Never Loop.
• 🎯 Why: To improve keyboard accessibility and speed up workflow for users navigating the Animation Controller UI. Mnemonics are a standard Swing feature that was missing on these specific buttons.
• 📸 Before/After: Not visually apparent unless holding Alt to reveal the underlined shortcut letters.
• ♿ Accessibility: Provides an alternative to mouse navigation by allowing direct selection and activation of primary animation controls via keyboard combinations.

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PR created automatically by Jules for task 13750215547298966320 started by @awest813

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