Flag missing conn-fields when hook-only files change in static checks

[dabla]

Currently, the check-provider-yaml-valid prek hook only fires when a
provider.yaml file is modified. When a developer adds a new field to
get_connection_form_widgets() in a hook Python file — as in PR #64643
which added auth_protocol to SambaHook — the static check is never
triggered, so the mismatch between the hook and provider.yaml goes
undetected.

There was also a second gap: even when the check did run, a
connection-type entry with no conn-fields section at all was
silently skipped, regardless of how many form widgets the hook declared.

This PR closes both gaps:

1. Trigger on hook file changes

check-provider-yaml-valid in providers/.pre-commit-config.yaml now
also fires when any file matching
src/airflow/providers/**/hooks/*.py is staged.
check_provider_yaml_files.py maps each changed hook file to the
provider.yaml at the root of the same provider package and passes
that to the in-container validator, so the full conn-fields check runs
even when only the hook changes.

2. Flag absent conn-fields when the hook declares widgets

check_conn_fields_for_entry() previously returned early with no error
when conn-fields was absent from provider.yaml. It now treats an
absent conn-fields section as an empty dict, so every field returned
by get_connection_form_widgets() is reported as missing — exactly the
same error the existing bidirectional check already produces for a
present-but-incomplete conn-fields section.

Changes

File	What changed
scripts/ci/prek/check_provider_conn_fields.py	Treat absent conn-fields as {} instead of short-circuiting
scripts/ci/prek/check_provider_yaml_files.py	Map hook Python files → provider.yaml before delegating to Breeze
providers/.pre-commit-config.yaml	Expand trigger to include hooks/*.py files
scripts/tests/ci/prek/test_check_conn_fields_match_form_widgets.py	Replace the "no-conn-fields-with-hook-widgets-is-ok" passing case with a failing case; add absent-conn-fields-with-hook-widgets error test

Reproduction

Without this fix, the following scenario produces no CI error:

# provider.yaml — no conn-fields section at all
connection-types:
  - hook-class-name: airflow.providers.samba.hooks.samba.SambaHook
    connection-type: samba

# samba.py
@classmethod
def get_connection_form_widgets(cls):
    return {"auth_protocol": SelectField(...)}  # invisible in React UI!

With this fix, the static check reports:

Mismatch between conn-fields in providers/samba/provider.yaml and
SambaHook.get_connection_form_widgets() for connection-type 'samba':
  Fields in get_connection_form_widgets() but NOT in provider.yaml conn-fields: auth_protocol
How to fix it: Add the missing key(s) to conn-fields in provider.yaml.

---

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Claude Sonnet 4.6

---

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[github-actions]

uv.lock on main just moved via #70087 ("Add AWS services toolset for agents to access 1000+ APIs"), commit eddaa67 and this PR currently conflicts.

Quickest fix:

git fetch upstream main && git rebase upstream/main
rm uv.lock && uv lock
git add uv.lock && git rebase --continue
git push --force-with-lease

Automated nudge — ignore if you're not ready to rebase. This comment is updated in place on future uv.lock bumps.

[github-actions]

Backport successfully created: v3-3-test

Note: As of Merging PRs targeted for Airflow 3.X
the committer who merges the PR is responsible for backporting the PRs that are bug fixes (generally speaking) to the maintenance branches.

In matter of doubt please ask in #release-management Slack channel.

Status	Branch	Result
✅	v3-3-test