Database as a context manager, fixed many pytest warnings

* Database can now work as a context manager
* Claude Code helped fix a ton of .close() warnings

https://gistpreview.github.io/?730f0c5dc38528a1dd0615f330bd5481

* New autouse fixture to help with test warnings

Refs https://github.com/simonw/sqlite-utils/issues/692#issuecomment-3644371889

* Fix all remaining resource warnings

https://gistpreview.github.io/?0bb8e869b82f6ff0db647de755182502

Closes #692

tests/test_recreate.py

@@ -14,8 +14,11 @@ def test_recreate_ignored_for_in_memory():
 
 def test_recreate_not_allowed_for_connection():
     conn = sqlite3.connect(":memory:")
-    with pytest.raises(AssertionError):
-        Database(conn, recreate=True)
+    try:
+        with pytest.raises(AssertionError):
+            Database(conn, recreate=True)
+    finally:
+        conn.close()
 
 
 @pytest.mark.parametrize(