Configured Gemini API key and applied dark theme

[anushkaa03]

🔗 Related Issue

🎯 Rationale

• Adds support for Google Gemini API by configuring the API key in .streamlit/secrets.toml.
• Implements dark mode for the entire application with consistent styling for buttons, inputs, text, and charts.
• Improves user experience with theme toggling and responsive mobile layout.

📝 Summary of Changes

• Configured Gemini API key integration in the project.
• Added dark mode toggle button on the top navigation.
• Applied dark mode styling across all pages and components.
• Ensured responsive design for mobile and desktop.

🔧 Technical Details

• Updated secrets.toml handling to load GEMINI_API_KEY.
• Modified Streamlit CSS dynamically to support dark/light themes.
• Updated navigation buttons and feature cards to adapt colors based on theme.
• Dark mode state stored in st.session_state for persistence across pages.

✅ Testing

• Test Coverage
• Manual testing completed
• Unit tests added/updated
• Integration tests added/updated
• All existing tests pass
• Test Details
• Verified Gemini API key is loaded correctly and app communicates with the backend.
• Tested dark mode toggle on desktop and mobile screen sizes.
• Confirmed all buttons, inputs, and charts render correctly in both themes.

📚 Documentation

• Code comments updated
• README updated (optional)
• API documentation updated
• Migration guide provided
• 🔄 Breaking Changes
• This PR contains breaking changes

🎨 User-Facing Changes

• Frontend Changes
• UI components modified for dark mode
• New user interactions added
• Styling/theme changes applied
• Backend/API Changes
• Existing endpoints configured to use GEMINI_API_KEY

📋 Checklist

• Code Quality
• Code follows project style guidelines
• Self-review completed
• No debug statements left
• Error handling implemented appropriately
• Review Readiness
• PR title is descriptive and follows conventions
• PR description is complete and accurate
• Commits are atomic and well-documented
• Branch is up to date with target branch
• Security & Performance
• No sensitive information exposed (GEMINI_API_KEY is local only, ignored by Git)
• Performance impact considered
• Security implications reviewed

🚀 Deployment Notes

• Ensure .streamlit/secrets.toml contains GEMINI_API_KEY for deployment.
• No database migrations required.

📸 Screenshots/Demo
-Before

-After

Reviewer Notes

• Focus on dark mode consistency across all components.
• Verify that GEMINI_API_KEY integration works as expected.
• No known limitations; user feedback welcomed.