[agrawalmilin9]

Closes #21

Summary

• Add a Dockerfile for the UberClone backend.
• Add Docker Compose services for backend startup and one-time Mumbai road-data preparation.
• Persist road data and the SQLite database in named Docker volumes.
• Add .dockerignore to reduce the Docker build context.
• Document Docker startup and phone-access instructions in RUNNING.md.

Testing

• docker compose config — passed.
• docker compose up --build -d — successful.
• Backend health check — HTTP 200, {"status":"ok"}.
• Python tests — 177 passed, 1 skipped, 16 subtests passed.
• Mobile typecheck and lint — passed.
• Mobile unit tests — 31 passed.