Prepaid Credits & New Billing

✨ New Features

• Prepaid Credits: Monthly quotas are gone. You spend credits on blogs, social posts, images, research, SEO, and more. Same system in the app and for connected agents.
• Credit Packs: Top up anytime from Billing. Purchased credits do not expire.
• Monthly Allowance: Your plan still includes a monthly credit allowance. That pool is used first; top-ups cover the rest.
• Automatic Refunds: If a job fails after credits were spent, those credits come back.
• Usage History: See what you spent credits on from a history dialog in Billing.

🧹 Improvements

• Billing Page: Cleaner layout with balance, plan, Add credits, and manage-subscription controls in one place.
• Navbar Credit Chip: Your balance sits in the navbar. Open it for a quick overview without leaving the page.
• Updated Pricing: Pro is $27/mo and Max is $67/mo (shown with the previous price struck through). Annual pricing is unchanged at $22 and $54.

🛠 Fixes

• Paid Plan Detection: Fixed cases where a paid account could be treated as free when billing details failed to load.