Creem payment provider, reworked navigation with quick search

Creem.io joins our supported payment providers, and it's now the default for PayGlue's own billing too, so your subscription, invoice history, and plan details all read from Creem. The dashboard navigation also got a rework: sections expand in place instead of jumping to a separate tab row, and a quick search (⌘K) jumps straight to any page.

• Creem connection: buy buttons, paywalls, and pricing tables all support it end to end
• Billing page now shows your real plan name, next payment date, and invoice history from Creem
• Expandable sidebar sections with a clearer breadcrumb
• Press ⌘K (or click search) to jump to any page instantly
• Same navigation on mobile as on desktop