Change starlette import to fastapi

[unknowntpo]

Description

This PR change starlette import to fastapi, fastapi re-export starlette dependencies for convenience and consistency, we should use it if possible.

However, the following starlette imports must remain because FastAPI does not re-export these modules:

BaseHTTPMiddleware

Why: FastAPI intentionally does not re-export BaseHTTPMiddleware. There is no fastapi.middleware.base module.

References:

• Add BaseHTTPMiddleware to FastAPI fastapi/fastapi#8541 - Request to add BaseHTTPMiddleware to FastAPI was answered with: "Is there a particular reason you don't just import it directly from Starlette, since FastAPI depends on Starlette?" (marked as accepted answer)
• https://fastapi.tiangolo.com/advanced/middleware/ - FastAPI only re-exports specific middlewares (HTTPSRedirect, TrustedHost, GZip, WSGI, CORS), not BaseHTTPMiddleware.

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• related: Migrate FAB POST /roles to FastAPI #57199 (comment), Refactor imports to use FastAPI modules instead of Starlette #58127 (this PR is stale)

Was generative AI tooling used to co-author this PR?

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Generated-by: [Cursor, Claude] following the guidelines

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[boring-cyborg]

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[jason810496]

Thanks for the PR! LGTM overall.

https://github.com/apache/airflow/actions/runs/20886590921/job/60010997219?pr=60382 Some static checks still need fix, thanks!

[boring-cyborg]

Awesome work, congrats on your first merged pull request! You are invited to check our Issue Tracker for additional contributions.