Design overhaul and subscription billing

I reworked the design: a navy palette, a single top nav, and a light, dark, or system theme picker. The status page got a 90-day activity timeline, compact card rows, a bio, and platform links. I set the plan at a single $49 a month, after briefly trying $199, and built subscription billing on Stripe with banners for past-due and canceled accounts and a grace period. Handles became permanent and case-insensitive, and I added Google and Apple sign-in, Privacy and Terms pages, and a How It Works guide after claiming a handle.