fix: elevate plugin discovery failures from debug to warning

Plugin discovery exceptions in gateway startup (gateway/run.py) and
CLI startup (hermes_cli/main.py) are caught and logged at DEBUG
level, making them invisible at the default INFO log level.

If any plugin import fails — syntax error, missing dependency, import
cycle — operators get zero indication unless they bump the log level
to DEBUG. This makes broken plugins appear enabled but silently
non-functional.

Change both locations to logger.warning() so failures are visible at
production log levels.

Closes #28137

gateway/run.py

@@ -3474,7 +3474,7 @@ class GatewayRunner:
             from hermes_cli.plugins import discover_plugins
             discover_plugins()
         except Exception:
-            logger.debug(
+            logger.warning(
                 "plugin discovery failed at gateway startup", exc_info=True,
             )
 

hermes_cli/main.py

@@ -12672,7 +12672,7 @@ Examples:
 
             discover_plugins()
         except Exception:
-            logger.debug(
+            logger.warning(
                 "plugin discovery failed at CLI startup",
                 exc_info=True,
             )