bug fix for dynamic routing logic

fix: use .get() for all state access to prevent KeyError in graph nodes

chore: add structured logging across backend

chore: clean DB, enable static mount, update env for deploy

fix: interview turn limits, LLM fallback, and completion UI

bug fix on chat page

updated ui, docs, tests

feat: register batches, topics, upload routers in main.py

feat: upload router — parse CSV and bulk insert questions

feat: topics router — create, list, unlock/lock

feat: batches router — create, get mine, get by id

feat: add batch/topic/question DB queries

feat: add CSV question parser utility with unit tests

feat: add NeonDB schema (all tables) and apply_schema script

fix: auth quality issues — token cleanup, delete_cookie params, broad exception catch, dead import

feat: implement auth router (signup/login/refresh/logout) and FastAPI deps

feat: implement NeonDB SQL queries for users and refresh tokens

feat: implement asyncpg connection pool

fix: add JWT secret warning and missing security tests

feat: implement JWT access token and refresh token generation

feat: implement bcrypt password hashing

chore: add .env.example, Dockerfile, and .gitignore; remove pycache from tracking

chore: add backend directory structure and stub files