Debug: fix headless mode, plugin compat, psutil optional, module imports

- headless: TUI skip now works correctly
- example_plugin: keyword args compat (plugin_name=, config=, bridge=)
- sysmon: psutil made optional (graceful degrade)
- tui_service: SysMonWidget optional
- All 22 modules import clean, 23 tests pass, integration verified

plugins/example_plugin/__init__.py

@@ -14,8 +14,8 @@ except ImportError:
 logger=logging.getLogger(__name__)
 
 class Plugin:
-    def __init__(self,n,c,bridge):
-        self.plugin_name=n;self.config=c;self.bridge=bridge
+    def __init__(self, plugin_name=None, config=None, bridge=None, n=None, c=None):
+        self.plugin_name=plugin_name or n;self.config=config or c;self.bridge=bridge
         self.network_bridge=None;self.is_running=False
 
     async def initialize(self):