Python Firebase OTP Auth App

I need a small web application built in Python that uses Firebase’s phone-number OTP flow to gate access to a single Admin dashboard. After I enter my registered phone number, Firebase should send the code, verify it, and then route me to a protected page; all other pages remain inaccessible unless the token is valid.

The interface can stay extremely simple—plain HTML/CSS with minimal styling is enough. No email logins, social logins, or multi-role logic are required right now; just the Admin pathway.

Deliverables
• Python source (Flask, FastAPI, or Django—choose what you feel is lightest)
• Firebase project configuration and environment variables clearly separated in a .env file
• One protected dashboard route that simply confirms the successful login (I’ll extend it later)
• README with step-by-step setup for local run and generic Linux deployment

Acceptance criteria
• OTP sent and verified via Firebase; incorrect or expired codes are gracefully handled
• After successful verification, the Admin session persists until logout or token expiry
• Unauthenticated users redirected to the login page on any protected route

Mention any lightweight templates or libraries you intend to use when you bid so I can keep future maintenance straightforward.