Refactor: Simplify auth flow and improve neural mesh update synchronization

feat: replace sign up/sign in with single 'Enter' flow

fix: strict user isolation — remove all user_id IS NULL leaks

feat: clean slate on every sign-in — wipe all prior user data

feat: auto-build neural mesh from chat conversations

fix: normalize usernames and ensure case-insensitive authentication

feat: Implement secure Authentication system with JWT and AuthScreen UI

fix: Use IS NULL for Neo4j legacy compatibility across all graph queries

fix: Graph rendering with legacy data + Brain-organic color palette overhaul

feat: Add generative visual dream sequence gallery

feat: Add Multi-User Persona memory compartmentalization

Phase 3 Complete: Background dreaming and Neural Spark log implemented.

Phase 2 Complete: Real-time Neural Mesh highlighting implemented.

Phase 1 Complete: Implemented Internal Reflection node and Monologue UI.

Final Evolution: Secure Neural Build (Full Scrub & Sync)

feat: Establish initial FastAPI project with core configuration, API endpoints, and a basic Langgraph orchestrator.