Full-Stack React/Firebase Expert – App Security Audit & Performance Optimization (One-Shot Mission)

We are looking for a senior-level developer to perform a comprehensive review and "cleanup" of our AI-powered web application. The app is built using React (Vite), TypeScript, and Firebase. It leverages the Google Gemini Multimodal Live API for real-time text-to-speech (TTS) and AI simulations. We recently encountered a project suspension from Google Cloud due to a suspected API key leak/resource abuse. We need an expert to secure the environment and ensure the platform is production-ready. Your Mission: Security Audit: Review our API key management and implementation. Ensure all keys (Gemini, Firebase, etc.) are restricted by domain/referrers and properly secured. Infrastructure Cleanup: Audit the current Google Cloud/Firebase configuration. Resolve target mismatch issues (e.g., Site Not Found errors) and clean up redundant deployment targets. Performance & Stability: Optimize the app’s loading speed, specifically the pre-loading phase of AI simulations. Review the current logic for npm audit vulnerabilities and perform safe dependency updates (Firebase Admin SDK v13+, etc.). Bug Fixing: Resolve minor UI/UX logic issues, such as voice/gender mismatches in AI profiles. Deployment Workflow: Ensure the PowerShell/Firebase CLI deployment pipeline is clean and repeatable. Required Skills: Expertise in React (TS) and Firebase (Firestore, Auth, Hosting). Strong experience with Google Cloud Platform (GCP) security and API management. Experience with Google Gemini API or similar LLM integrations. Deep understanding of web security best practices (CORS, API restrictions, environment variables). Ability to work with Legacy/Existing codebases and perform "surgical" fixes without breaking functionality. Project Details: Type: One-time project (One-shot). Timeline: Immediate start preferred.