Move flat tests/integration/test_*.py files into thematic subfolders
(action_plugins, application_id, categories, compose, domains, filters,
handlers, jinja, linting, oauth2_oidc, passwords, ports, roles, run_once,
services, workflows), strip redundant prefixes from filenames, and
adjust path-depth references by +1 level. Add __init__.py and a scope-
focused README.md per cluster so the directory purpose is discoverable
without duplicating the integration.md SPOT. Update design/services.md
to point at the new test locations.
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>