🎨 Palette: Replace save alert with inline feedback

[dhaatrik]

💡 What

• Replaced the blocking alert('Blueprint saved!') in VABEditor with inline text/class modifications on the save button.
• Added :hover states for .vab-save-btn and .vab-cancel-btn in public/style.css.
• Added a .success state for the save button to temporarily turn green and display "Saved!".

🎯 Why

• Blocking alert dialogs disrupt the user's flow and provide a jarring, unpolished experience.
• The save button was missing standard interaction cues like hover states, making the UI feel unresponsive.
• Temporary inline feedback keeps the user in context while confirming their action succeeded.

📸 Before/After

Before: Clicking "Save" popped up a browser-native alert dialog "Blueprint saved!" that completely blocked the UI. Buttons had no visual response on hover.
After: Clicking "Save" immediately changes the button text to "Saved!", turns the background green for 2 seconds, and gracefully transitions back. Buttons now subtly lighten on hover.

♿ Accessibility

• Added aria-live="polite" to the save button during the success state so screen readers will automatically announce "Saved!" without needing an alert dialog. The attribute is dynamically added and removed after the 2 second duration.
• Maintains keyboard operability and preserves correct ARIA states during the transition.

---

PR created automatically by Jules for task 4483956043458351530 started by @dhaatrik

[google-labs-jules]

👋 Jules, reporting for duty! I'm here to lend a hand with this pull request.

When you start a review, I'll add a 👀 emoji to each comment to let you know I've read it. I'll focus on feedback directed at me and will do my best to stay out of conversations between you and other bots or reviewers to keep the noise down.

I'll push a commit with your requested changes shortly after. Please note there might be a delay between these steps, but rest assured I'm on the job!

For more direct control, you can switch me to Reactive Mode. When this mode is on, I will only act on comments where you specifically mention me with @jules. You can find this option in the Pull Request section of your global Jules UI settings. You can always switch back!

New to Jules? Learn more at jules.google/docs.

---

For security, I will only act on instructions from the user who triggered this task.