v2.16.14 — Guest auth fix & bookmark terminology

Summary

• Fix: Content intelligence and other tools now work for unauthenticated visitors — auto-provisions a guest hash bookmark on page load
• Fix: Replaced all "Login" / "Sign in" / "Please log in" UI messaging with bookmark-appropriate language across 24 files (en + es)
• Root cause: Security audit commit neutered getUserIdOrDefault (correctly fixing IDOR) but didn't add a guest provisioning replacement

Changes

• Added ensureAuthIdentifier() in auth-utils.ts — auto-generates hash bookmark for guests
• ContentIntelligencePage calls it on mount, removing the auth gate
• Dashboard header: "Login" button → "Save Bookmark" with Save icon
• All 401 error messages → "Session expired. Please refresh to continue."
• Backend error messages updated (auth-helpers, middleware, social-media API)
• i18n translations updated for both English and Spanish

Files Changed

24 files across frontend pages, components, API handlers, and i18n translations