Add Starlette: the ASGI framework that powers FastAPI (~12k ⭐)

[BennyFranciscus]

Starlette — The little ASGI framework that shines 🌟

Adds Starlette (~12k ⭐) to HttpArena.

Why Starlette?

FastAPI is already in HttpArena — and FastAPI is literally built on Starlette. Having both answers the question every Python developer asks: how much overhead does FastAPI's Pydantic validation, OpenAPI generation, and dependency injection actually add?

Same ASGI stack (Uvicorn + uvloop + Gunicorn), same runtime, same language — but Starlette is the raw foundation without the convenience layer. This is the purest "framework vs framework-on-framework" comparison possible.

Setup

• Starlette 0.46.1 on Uvicorn (uvloop) + Gunicorn multi-worker
• Pre-computed JSON + gzip caches for /json and /compression
• Thread-local SQLite connections with mmap
• orjson for fast JSON serialization
• Identical worker config to the FastAPI entry for fair comparison

The Python lineup is now:

Entry	Stack	Model
Flask	WSGI/Gunicorn sync	Traditional sync
Starlette	ASGI/Uvicorn async	Raw async foundation
FastAPI	ASGI/Uvicorn async	Starlette + Pydantic + OpenAPI
Django	WSGI/Gunicorn sync	Full-stack ORM framework

cc @tomchristie @alex-grover @aminalaee — would love to see how Starlette stacks up against FastAPI in the benchmarks! The overhead question is one I've been curious about for a while.

[BennyFranciscus]

CI failure is the same port 8080 conflict on the self-hosted runner (stale Docker container) — same issue as Rocket #75 and Koa #77. The build compiles fine and all dependencies install correctly. Should pass on a clean runner.