Fix plugin config lookup shadowed by CLIENT_DEFAULTS plugins key

CLIENT_DEFAULTS seeds "plugins": {} so raw_config.get("plugins", raw_config)
always returned the empty subdict instead of falling back to the full config.
Plugins configured at top-level (e.g. nagios_runner: ...) were therefore
never found, resulting in "No Nagios commands configured".

Now checks the plugins subdict first, then top-level keys, so both
config layouts work correctly.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

hbd/client/plugin.py

@@ -312,9 +312,10 @@ class PluginLoader:
         
         loaded_count = 0
         raw_config = config or {}
-        # Per-plugin config lives under the 'plugins' key; fall back to top-level
-        # for backwards compatibility.
-        plugin_config = raw_config.get("plugins", raw_config)
+        # Per-plugin config lives under the 'plugins' key or at top-level.
+        # CLIENT_DEFAULTS seeds "plugins": {} so the key always exists; check
+        # both the subdict and top-level so that either layout in .hbc.yaml works.
+        plugins_subconfig = raw_config.get("plugins", {})
         
         # Scan for Python files
         for plugin_file in directory.glob("*.py"):
@@ -359,8 +360,9 @@ class PluginLoader:
                     
                     self.logger.debug(f"Found plugin class: {name}")
                     
-                    # Instantiate plugin with config
-                    plugin_instance_config = plugin_config.get(obj.name, {})
+                    # Instantiate plugin with config — check plugins subdict first,
+                    # then top-level keys (e.g. nagios_runner: ... at root of config).
+                    plugin_instance_config = plugins_subconfig.get(obj.name) or raw_config.get(obj.name, {})
                     plugin = obj(config=plugin_instance_config)
                     
                     # Initialize plugin