feat(phase-3): implement react frontend and realtime audio hooks

[PyDevDeep]

Title: feat(phase-3): Implement React frontend and real-time audio hooks

Description
Completed Phase 3 (Frontend) of the project roadmap. Implemented the Vite + React client application using Tailwind CSS for styling and native Web Audio API for PCM16 audio processing.

Changelog

1. React Setup & Configuration

• frontend/package.json & vite.config.js: Initialized Vite React project. Configured dev server proxy to bypass CORS and route /api and /ws requests to the FastAPI backend running on port 8000.
• frontend/tailwind.config.js & globals.css: Configured Tailwind CSS utility classes.

2. Real-time Audio Processing

• frontend/src/hooks/useVoiceSession.js: Built a custom hook utilizing the Web Audio API (AudioContext, ScriptProcessor) to capture raw microphone input, convert Float32 arrays to 16-bit PCM at 24kHz, and stream binary chunks to the OpenAI Realtime API via FastAPI WebSockets. Implemented interrupt handling and binary audio playback for OpenAI responses.
• frontend/src/components/AudioWaveform.jsx: Implemented a native HTML5 Canvas visualizer driven by an AnalyserNode to render a real-time waveform of the user's voice input.
• frontend/src/components/VoiceWidget.jsx: Integrated the audio session hook and waveform visualizer into the primary user interface.

3. Admin Dashboard & WebSockets

• frontend/src/hooks/useAdminSocket.js: Implemented a resilient WebSocket client hook for the admin dashboard featuring an exponential backoff reconnection algorithm (up to 5 retries) to handle backend restarts.
• frontend/src/components/BookingTable.jsx: Extracted the booking table into a reusable component with strict color-coded statuses (Confirmed, On Hold, Cancelled).
• frontend/src/components/AdminDashboard.jsx: Integrated the admin socket to render live, zero-latency booking updates broadcasted by n8n and FastAPI.

Acceptance Criteria Checklist
[x] Frontend dependencies compile securely without ENOENT errors.
[x] useVoiceSession successfully converts Float32 to PCM16 and multiplexes binary streams.
[x] useAdminSocket algorithm enforces exponential backoff upon connection drops.
[x] AudioWaveform canvas accurately visualizes the frequency data from the AnalyserNode.
[x] dist/ and node_modules/ are strictly excluded from source control.