feat: add gTTS fallback to guarantee text-to-speech audio playback under rate limit

feat: optimize latency, implement global MutationObserver for instant audio play, and add user interrupt handlers for click and spacebar

feat: implement real-time continuous hands-free voice chat mode using Web Speech API VAD, global audio capture, and autoplay response

feat: add microphone voice input with automatic Groq Whisper STT transcription and TTS audio autoplay response

fix: change stream_to_file to write_to_file for new Groq SDK, sanitize all PDF text for Helvetica font

feat: add PDF export button, conversational welcome message, green theme, and verbose debug logging

fix: remove GEMINI_API_KEY guard that blocked all messages on HF Spaces

feat: simplify interface to a clean, simple chatbot layout

fix: restore button sizing to resolve layout breakage and non-clickable elements

fix: apply global SVG styling constraints to prevent giant icons

fix chatbot avatar icon styling sizes

Replace Streamlit with Gradio UI and update HF Spaces metadata

Add approach document and local UI