Add kanta.bootstrap logger and configurable logging setup

- Bootstrap records are now logged via kanta.bootstrap at INFO level.
- Existing databases log 'Using <path>' at DEBUG on kanta.bootstrap.
- New databases log 'Created <path>' at INFO on kanta.bootstrap.
- Renamed loggers: kanta.changes -> kanta.transaction, kanta.migrations -> kanta.migration.
- configure_logging() gains bootstrap/migration/transaction/skiproot kwargs.
- Default configure_logging() attaches a no-prefix stderr handler to kanta and stops propagation.
- With skiproot=False, child logger propagation flags are still applied but kanta itself is left untouched.
- Updated tests and docstrings.

tests/test_logging.py

@@ -1,15 +1,47 @@
 import logging
 
-from kanta.logging import changes_logger, configure_logging, log_change
+import pytest
+
+from kanta.logging import configure_logging, log_change, transaction_logger
 
 
-def test_configure_logging():
+@pytest.fixture(autouse=True)
+def _reset_kanta_loggers():
+    yield
+    for name in ("kanta", "kanta.transaction", "kanta.bootstrap", "kanta.migration"):
+        logger = logging.getLogger(name)
+        logger.setLevel(logging.NOTSET)
+        logger.propagate = True
+        logger.handlers.clear()
+
+
+def test_configure_logging_defaults():
+    kanta_logger = logging.getLogger("kanta")
     configure_logging()
-    assert changes_logger.level == logging.INFO
+    assert kanta_logger.level == logging.INFO
+    assert not kanta_logger.propagate
+    assert kanta_logger.handlers
+
+
+def test_configure_logging_disables_specific_loggers():
+    configure_logging(bootstrap=False, migration=False, transaction=False)
+    assert not logging.getLogger("kanta.bootstrap").propagate
+    assert not logging.getLogger("kanta.migration").propagate
+    assert not logging.getLogger("kanta.transaction").propagate
+
+
+def test_configure_logging_skiproot_false_leaves_kanta_propagation():
+    kanta_logger = logging.getLogger("kanta")
+    kanta_logger.handlers.clear()
+    configure_logging(bootstrap=False, skiproot=False)
+    assert kanta_logger.propagate
+    assert not kanta_logger.handlers
+    assert not logging.getLogger("kanta.bootstrap").propagate
 
 
 def test_log_change_no_diff(capsys):
-    changes_logger.handlers.clear()
+    kanta_logger = logging.getLogger("kanta")
+    kanta_logger.handlers.clear()
     configure_logging()
     log_change("test", {})
     captured = capsys.readouterr()