Move soup_cli/ -> src/soup_cli/ (history preserved via git mv). src-layout
forces the test suite to import the installed package instead of the
repo-root source tree, surfacing packaging bugs that flat-layout masks —
e.g. the v0.53.8 double-shipped-fixtures regression, invisible because
`pytest tests/` imports ./soup_cli directly and never from the wheel.
- pyproject: packages = ["src/soup_cli"]; artifacts globs -> src/soup_cli/...
The import name is unchanged, so the `soup` entry point, --cov=soup_cli,
and report_to/module-path strings stay `soup_cli`.
- CI / ownership: ruff lint path (ci.yml), recipe-validation `paths:` filters,
CODEOWNERS patterns, and the PR-template checklist all repointed to
src/soup_cli/.
- tests: source-grep regression tests that read package files by repo-relative
path repointed to src/soup_cli/ (64 files; 170 path literals). Lines pushed
over 100 chars by the prefix were wrapped to keep ruff E501 clean. Module
references (`import soup_cli`, `-m soup_cli`, mock.patch("soup_cli.x")) and
the `--cov=soup_cli` coverage target are deliberately unchanged.
- docs: AGENTS.md + CONTRIBUTING.md structure tree and lint commands.
Verified locally: ruff clean (src/soup_cli + tests); `import soup_cli`
resolves to src/soup_cli/__init__.py; built wheel ships
soup_cli/data/_fixtures/*.jsonl (10 files, no duplicates, no src/ prefix);
3174 tests across every touched test file pass. Packaging-only — no version bump.