refactor(logging): preserve tracebacks and add channel context

- Preserve tracebacks: logger.error in except blocks → logger.exception
- Channel context: BaseChannel injects self.logger = logger.bind(channel=name)
- Third-party bridge: redirect_lib_logging() replaces ad-hoc stdlib-to-loguru bridges
- Log levels: network timeouts downgraded from ERROR → WARNING
- Fix --verbose flag to actually work with loguru (set handler to DEBUG)

nanobot/utils/logging_bridge.py

@@ -0,0 +1,47 @@
+"""Utilities for redirecting stdlib logging to loguru."""
+from __future__ import annotations
+
+import logging
+
+from loguru import logger
+
+
+class _LoguruBridge(logging.Handler):
+    """Route stdlib log records into loguru with consistent formatting."""
+
+    _LEVEL_MAP: dict[int, str] = {
+        logging.DEBUG: "DEBUG",
+        logging.INFO: "INFO",
+        logging.WARNING: "WARNING",
+        logging.ERROR: "ERROR",
+        logging.CRITICAL: "CRITICAL",
+    }
+
+    def __init__(self, lib_name: str) -> None:
+        super().__init__()
+        self.lib_name = lib_name
+
+    def emit(self, record: logging.LogRecord) -> None:
+        level = self._LEVEL_MAP.get(record.levelno, "INFO")
+        frame, depth = logging.currentframe(), 2
+        while frame and frame.f_code.co_filename == logging.__file__:
+            frame, depth = frame.f_back, depth + 1
+        logger.opt(depth=depth, exception=record.exc_info).log(
+            level, "[{lib}] {message}", lib=self.lib_name, message=record.getMessage()
+        )
+
+
+def redirect_lib_logging(name: str, level: str | None = None) -> None:
+    """Redirect stdlib logging from *name* into loguru.
+
+    Adds a bridge handler if one is not already present and disables
+    propagation so messages are not duplicated.  When *level* is None the
+    handler does not filter — loguru's own level controls visibility.
+    """
+    lib_logger = logging.getLogger(name)
+    if not any(isinstance(h, _LoguruBridge) for h in lib_logger.handlers):
+        handler = _LoguruBridge(name)
+        if level is not None:
+            handler.setLevel(getattr(logging, level.upper(), logging.WARNING))
+        lib_logger.handlers = [handler]
+        lib_logger.propagate = False