fix: resolve CastError by making ApiKey model NeDB-compatible

feat: integrate sk-cdx API keys and Qwen3-Coder-480B engine

Production Fix: Resolve fs ReferenceError in Multer, fix profile auth failure, and optimize controller lookups

System Stability Patch: Fix trust proxy, chainable NeDB models, absolute upload paths, and sentinel stack safety

Critical Fix: Resolve 401 'Subject not found' loop, stabilize HF Space persistence, and improve session recovery

Strategic Migration: Complete NeDB Architecture with Cloud Persistence and Image Recognition Fixes (Clean)

initial