fix: implement OpenRouter multi-model fallback loop and clean markdown JSON wrappers

fix: display detailed API errors in fallback message

fix: read API keys directly from os env to bypass Pydantic binding issues

fix: remove fallback notice banner and optimize mock keyword match

feat: upgrade OpenRouter fallback to DeepSeek V4 Flash Free model

fix: cleanup llm_chain code and stabilize fallback logic

fix: resolve syntax error in llm_chain.py

feat: integrate Groq & OpenRouter failover to achieve cost-free LLM routing

feat: add keep-alive workflow with random sleep bypass

feat: update UI, block YouTube, optimize history rankings click with cache

trigger: force deploy after space recreated

fix: revert YouTubeTranscriptApi call to correct class method and dictionary key access

trigger: deploy to Hugging Face Space

fix: resolve YouTubeTranscriptApi attribute error in newer library versions

feat: setup Docker and CI/CD deploy pipeline for Hugging Face Space