Session 5: Rebuild frontend as Vite+React 3-panel website builder IDE

frontend: fix StackBlitz launcher (was opening default Next.js starter)

Tier 2: image upload, vision toggle, StackBlitz/CodeSandbox launchers, UI polish

Tier 1: identity anchor + conversation memory + cleaner output

frontend: persistent auth-blocked state + actionable inline message

Add HF Space backend and frontend with HF token auth

feat: initial project scaffold for MINDI 1.5 Vision-Coder