Add public setup_logging() for standalone pretty logging

Optionally usable early in CLI mains, devservers and scripts that log
before (or without) server.run().  Shares patch_log_config with the
server path (same log_config overrides), but installs no server-side
patches: Formatter gains an install flag gating the lifespan/error
middleware monkeypatches, and the NullHandler backdoor is skipped.
dev=None follows env.dev for the root level, True/False override it.
Pre-existing loggers survive the dictConfig (disable_existing_loggers
is set False).

fastapi-vue/fastapi_vue/__init__.py

@@ -1,6 +1,7 @@
 """FastAPI Vue integration - serve Vue frontend from FastAPI."""
 
 from .environ import env, teleport
+from .logging import setup_logging
 from .staticfiles import Frontend
 
-__all__ = ["Frontend", "env", "teleport"]
+__all__ = ["Frontend", "env", "setup_logging", "teleport"]