docs: list all records search sources

[JordanCoin]

Closes #70

Summary

• list every live records search source in CLI help
• document all nine search adapters and distinguish cross-reference-only sources
• state the current third-party query disclosure behavior plainly
• add a regression test that keeps help aligned with the live registry

Verification

• python -m pytest tests/test_records_cli.py -v
• ruff check openfoia/cli.py tests/test_records_cli.py
• ruff format --check openfoia/cli.py tests/test_records_cli.py
• independent review: pass after correction

The full suite reached 279 passed and 26 skipped; two pre-existing LLM extraction tests require an unavailable local LLM and failed unchanged.

[Copilot]

Copilot was unable to review this pull request because the user who requested the review has reached their quota limit.