Add table-native backends, CLI, benchmarks, and PyMongo compatibility

[schapman1974]

Summary

• add CLI commands for inspecting, importing, exporting, and migrating TinyMongo data
• move SQLite, DuckDB, and Parquet from blob-style storage to table-native collection backends
• compile supported Mongo-style filters into SQL over _id and JSON document payloads, with Python fallback for unsupported shapes
• add legacy blob-file migration for SQLite and DuckDB files when opened
• document TinyDB, table-native SQLite, table-native DuckDB, and DuckDB-managed Parquet backends with refreshed benchmark results
• add integration stress tests for concurrent writes and fix default JSON storage races with atomic locked writes
• expand PyMongo-style compatibility with MongoClient URI handling, constants, server/listing helpers, and contract tests
• broaden unit coverage for query/update/index/result/error/CLI/table backend behavior

Verification

• .venv/bin/python -m coverage run -m pytest -q
• .venv/bin/python -m pytest -q -m integration tests/integration/test_concurrent_writes.py
• .venv/bin/python -m coverage report --include='tinymongo/*' -> 100%
• .venv/bin/python -m ruff check .
• .venv/bin/python -m build
• .venv/bin/python -m twine check dist/*
• .venv/bin/python tests/benchmarks/bench_storage.py --docs 1000 --queries 200 --json-output /tmp/tinymongo-table-backend-load-1000.json