fix: shutdown context, double IPC registration

- Run() uses context.Background() for shutdown (c.context is cancelled)
- Stoppable closure uses context.Background() for OnShutdown
- WithService delegates HandleIPCEvents to RegisterService only

Fixes Codex review findings 1, 2, 3.

Co-Authored-By: Virgil <virgil@lethean.io>

contract.go

@@ -169,15 +169,7 @@ func WithService(factory func(*Core) Result) CoreOption {
 			return Result{E("core.WithService", Sprintf("service name could not be discovered for type %T", instance), nil), false}
 		}
 
-		// IPC handler discovery
-		instanceValue := reflect.ValueOf(instance)
-		handlerMethod := instanceValue.MethodByName("HandleIPCEvents")
-		if handlerMethod.IsValid() {
-			if handler, ok := handlerMethod.Interface().(func(*Core, Message) Result); ok {
-				c.RegisterAction(handler)
-			}
-		}
-
+		// RegisterService handles Startable/Stoppable/HandleIPCEvents discovery
 		return c.RegisterService(name, instance)
 	}
 }

core.go

@@ -80,7 +80,7 @@ func (c *Core) Run() {
 		r = cli.Run()
 	}
 
-	c.ServiceShutdown(c.context)
+	c.ServiceShutdown(context.Background())
 
 	if !r.OK {
 		if err, ok := r.Value.(error); ok {

service.go

@@ -17,6 +17,8 @@
 
 package core
 
+import "context"
+
 // Service is a managed component with optional lifecycle.
 type Service struct {
 	Name     string
@@ -109,7 +111,7 @@ func (c *Core) RegisterService(name string, instance any) Result {
 	}
 	if s, ok := instance.(Stoppable); ok {
 		srv.OnStop = func() Result {
-			if err := s.OnShutdown(c.context); err != nil {
+			if err := s.OnShutdown(context.Background()); err != nil {
 				return Result{err, false}
 			}
 			return Result{OK: true}