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/cli/commands.py

@@ -21,6 +21,22 @@ if sys.platform == "win32":
 
 import typer
 from loguru import logger
+
+# Remove default handler and re-add with unified nanobot format
+logger.remove()
+_log_handler_id = logger.add(
+    sys.stderr,
+    format=(
+        "<green>{time:YYYY-MM-DD HH:mm:ss}</green> | "
+        "<level>{level: <5}</level> | "
+        "<cyan>{extra[channel]}</cyan> | "
+        "<level>{message}</level>"
+    ),
+    level="INFO",
+    colorize=None,
+    filter=lambda record: record["extra"].setdefault("channel", "-") or True,
+)
+
 from prompt_toolkit import PromptSession, print_formatted_text
 from prompt_toolkit.application import run_in_terminal
 from prompt_toolkit.formatted_text import ANSI, HTML
@@ -597,9 +613,19 @@ def gateway(
 ):
     """Start the nanobot gateway."""
     if verbose:
-        import logging
-
-        logging.basicConfig(level=logging.DEBUG)
+        logger.remove(_log_handler_id)
+        logger.add(
+            sys.stderr,
+            format=(
+                "<green>{time:YYYY-MM-DD HH:mm:ss}</green> | "
+                "<level>{level: <5}</level> | "
+                "<cyan>{extra[channel]}</cyan> | "
+                "<level>{message}</level>"
+            ),
+            level="DEBUG",
+            colorize=None,
+            filter=lambda record: record["extra"].setdefault("channel", "-") or True,
+        )
     cfg = _load_runtime_config(config, workspace)
     _run_gateway(cfg, port=port)
 

nanobot/cli/onboard.py

@@ -840,7 +840,7 @@ def _get_channel_info() -> dict[str, tuple[str, type[BaseModel]]]:
                 display_name = getattr(channel_cls, "display_name", name.capitalize())
                 result[name] = (display_name, config_cls)
         except Exception:
-            logger.warning(f"Failed to load channel module: {name}")
+            logger.warning("Failed to load channel module: {}", name)
     return result