Add prek hook to enforce HTTPException is imported from fastapi

[jason810496]

• related: UI: Fix HTTPException import that turned a 400 into a 500 in ui/dags  #67363

Why

fastapi.HTTPException, starlette.exceptions.HTTPException, and http.client.HTTPException are three different classes — mixing them silently breaks isinstance / pytest.raises checks, and http.client.HTTPException has a different constructor so routes return 500 instead of the intended status (the exact bug #67363 fixed in core_api/routes/ui/dags.py).

What

• Add scripts/ci/prek/check_http_exception_import_from_fastapi.py — an AST-based prek hook that flags any from <module> import HTTPException where <module> is not fastapi (or a fastapi.* submodule).
• Register it in .pre-commit-config.yaml, scoped to the FastAPI-using trees: airflow-core/src/airflow/api_fastapi/, airflow-core/tests/unit/api_fastapi/, and the src/ + tests/ of the providers that wire FastAPI apps (amazon, common/ai, edge3, fab, keycloak).

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

• Yes, with help of Claude Code Opus 4.7 following the guidelines

[jason810496]

I expect CI should fail before #67363 get merged.

[jscheffl]

I'd propose to keep the check general where it is but making the prek entries into the specific subfolders. e.g. the core things into /airflow-core/.pre-commit-config.yaml

[jscheffl]

That check willr aise false-positives. Edge containes both client and server sides.

All code in providers/edge3/src/airflow/providers/edge3/worker_api and providers/edge3/src/airflow/providers/edge3/plugins is the API/Server side but in providers/edge3/src/airflow/providers/edge3/cli is is the client (where the FastAPI import will be wrong!)