Add "YouTube Script Generator" Tool 📹

[Sappymukherjee214]

🚀 Is your feature request related to a problem? Please describe.

The platform already features a rich set of tools, but it currently lacks a dedicated tool for video creators. I'm always frustrated when I have to use a general "Creative" or "Casual" mode when I'm specifically trying to script a YouTube video with its unique structure, including an Intro/Hook, Main Content Body, and Call to Action (CTA).

💡 Describe the solution you'd like

I would like to add a dedicated "YouTube Script Generator" tool card in the Tools library. This includes:

• Adding a new tool entry to the tools array in frontend/src/components/Tools.tsx with a specific id: 'youtube-script' and an appropriate lucide-react icon (e.g., <Youtube /> or <Video />).
• Updating the getPlaceholder logic in frontend/src/App.tsx to provide clear, relevant instructions for video script inputs.
• Ensuring the backend can handle the new toolId by passing a specialized system prompt for video script formatting to the Google Gemini AI engine.

🎨 Describe alternatives you've considered

One alternative would be adding this as a sub-mode to the existing "Creative" mode. However, the current UI layout favors individual cards in the "Tools" tab, which makes specialized features much more discoverable and provides a better user experience for content creators.

📝 Additional context

This tool should follow the existing dashboard design system and integrate seamlessly with the Iterative Loop to ensure the generated script doesn't trigger AI detectors.