📈 Stock Return Calculator

Requirements:

1. API Integration (5 points)

Integrate the Alpha Vantage API to fetch historical stock price data.
Since the API does not provide exact minute-level data, you can:
- Use the average stock values for the day: (high + low) / 2
- OR allow users to choose between the high or low price range.
- The implementation details are left to you.
Allow users to input stock symbols, purchase dates, sell dates, and quantities to retrieve relevant data.

2. User Authentication (5 points)

Implement Firebase Authentication for user sign-up and login.
Ensure secure and personalized access to user portfolios and transaction history.

3. Profit/Loss Calculation (10 points)

Develop logic to calculate profit or loss based on fetched stock data and user inputs.
Display investment returns prominently to users after calculations.

4. User Interface (5 points)

Design an intuitive and responsive UI using Flutter widgets.
Include input fields for:
- Stock symbol
- Purchase date
- Sell date
- Quantity
Display the calculated profit or loss clearly and attractively.

5. Data Storage (5 points)

Store the last 5 calculated returns in Firestore, including:
- Stock name
- Buy date / Sell date
Ensure the stored data reflects recent calculations chosen by the user.