feat(frontend): refactor UI to clean anti-slop minimalist design with dual theme and image inspection

feat: optimize UI, SEO metadata for Google Search Console, and add reprocess fallback models

feat: implement frontend web application with background removal and Turnstile verification support

fix(hf): revert to standard demo.launch for ZeroGPU compatibility and add base64 API endpoint

fix: add /custom/upload FastAPI endpoint + fix Gradio file URL format per official docs

fix: send base64 ImageData directly to Gradio 6 (no /upload - not available in SSR mode)

fix: rewrite API route - upload to HF /upload first, then call /call/remove_bg, return base64

feat: add Next.js frontend for Vercel + enable Gradio API on HuggingFace