fix(web): remove XSS text corruption, fix scan count, add input validation, improve SSE polling

feat: add user authentication checks and improve navigation with logout functionality

v4.0: Fix analyze route — proper SSE parsing + immediate JSON file download

v4.0: Fix /api/analyze — call Gradio Space API directly instead of non-existent backend

v4.0: Web API analyze route — forward auth token to backend

Upload web/app/api/analyze/route.ts

Fix: /api/analyze default to HF backend (not localhost), /pricing → /#pricing (404 fix)

🛡️ ClauseGuard v1.0 — Full codebase: Extension + Website + API + ML