Convert linting from pylint/pycodestyle/pydocstyle to ruff

[awdeorio]

Summary

• Replace pycodestyle, pydocstyle, and pylint with a single ruff config that does both linting and formatting, matching the tooling already used in the chat485 trilogy and madoop.
• Drop .pylintrc and the tox pydocstyle glob hack (sh -c "pydocstyle agiocli tests/*"), which was needed because pydocstyle couldn't recurse into tests/.
• Fix the code flagged by the new rule set: ternary simplifications, unnecessary pre-return reassignments, a named constant for a magic year cutoff, tuple-form pytest.mark.parametrize IDs, and relocated/replaced noqa comments where a rule couldn't reasonably be satisfied by refactoring (e.g. PLR0913 on Click subcommands, which need one parameter per CLI option).
• Clean up agiocli/__init__.py: drop an unused from .utils import * wildcard re-export and switch the api_client re-exports to the explicit "import X as X" idiom, so no F401/F403 per-file-ignore is needed.
• Run ruff format once across agiocli and tests to normalize style.
• Update AGENTS.md and CONTRIBUTING.md to reference the new lint commands.

Test plan

• ruff check agiocli tests and ruff format --check agiocli tests pass
• check-manifest passes
• tox -e py3 passes end to end (lint, format check, check-manifest, pytest with coverage — 125 passed)
• grep sweep confirms no leftover pylint/pycodestyle/pydocstyle references