Reduce pro plan price in$120 per year#576

Currently, the Pro plan is expensive for many long-term users, especially those starting small.

I suggest adding an annual billing option for the Pro plan at $120 per year.

Benefits:

1. Encourages more users to commit long-term to Bitsgap
2. Reduces the burden of monthly payments for traders using bots consistently
3. Helps Bitsgap stay competitive with other platforms offering lower yearly rates

Many users are willing to pay annually if the price is more affordable. This would increase conversions and customer retention for Bitsgap while making the platform more accessible.