feat: WithName for explicit service naming

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

contract.go

@@ -178,6 +178,24 @@ func WithService(factory func(*Core) Result) CoreOption {
 	}
 }
 
+// WithName registers a service with an explicit name (no reflect discovery).
+//
+//	core.WithName("ws", func(c *Core) Result {
+//	    return Result{Value: hub, OK: true}
+//	})
+func WithName(name string, factory func(*Core) Result) CoreOption {
+	return func(c *Core) Result {
+		r := factory(c)
+		if !r.OK {
+			return r
+		}
+		if r.Value == nil {
+			return Result{E("core.WithName", Sprintf("failed to create service %q", name), nil), false}
+		}
+		return c.RegisterService(name, r.Value)
+	}
+}
+
 // WithOption is a convenience for setting a single key-value option.
 //
 //	core.New(

contract_test.go

@@ -59,6 +59,19 @@ func TestWithService_FactorySelfRegisters_Good(t *testing.T) {
 	assert.True(t, svc.OK, "expected self-registered service to be present")
 }
 
+// --- WithName ---
+
+func TestWithName_Good(t *testing.T) {
+	r := New(
+		WithName("custom", func(c *Core) Result {
+			return Result{Value: &stubNamedService{}, OK: true}
+		}),
+	)
+	assert.True(t, r.OK)
+	c := r.Value.(*Core)
+	assert.Contains(t, c.Services(), "custom")
+}
+
 // TestWithService_FactoryError_Bad verifies that a factory returning an error
 // causes New() to stop and propagate the failure.
 func TestWithService_FactoryError_Bad(t *testing.T) {