feat(outputs): write handoff reports and run history

[jaeyeopme]

Motivation

Persisted outputs are the next boundary before export orchestration. This PR adds deterministic handoff files and run history storage without coupling them to API or CLI entry points.

Scope

• Add clean CSV, clean JSON, rejected CSV, and run summary writers.
• Add standard output path construction for one export directory.
• Add SQLite run history insertion with documented count and output path fields.
• Add focused tests for output contracts and run history persistence.

Out of Scope

• Full export orchestration.
• API or CLI export behavior.
• Generated demo output files.
• Public docs status changes.

Modifications

• Add reports.py for deterministic clean and rejected output files plus a Markdown run summary.
• Add repository.py for inserting export run history into SQLite.
• Add tests that verify documented filenames, CSV columns, JSON payloads, summary sections, SQLite columns, and appended run ids.

Test Plan

• uv run pytest tests/test_reports.py tests/test_repository.py -v
• uv run ruff check src/clean_data_export_api/reports.py src/clean_data_export_api/repository.py tests/test_reports.py tests/test_repository.py
• uv run basedpyright
• uv run pytest -v
• uv run pytest tests/test_reports.py tests/test_repository.py --cov=clean_data_export_api.reports --cov=clean_data_export_api.repository --cov-report=term-missing
• uv run pytest --cov=clean_data_export_api --cov-report=term-missing --cov-fail-under=90
• uv run python -m compileall src tests
• git diff --check

Docs Impact

none

ADR Check

• No architecture or scope decision needs a new or updated ADR.

Result

Accepted and rejected rows can now be written to deterministic handoff files, and export run counts and output paths can be stored in SQLite.