feat: Add feature system to Core (#17)

This commit introduces a new feature system to the Core struct.

A new `Features` struct is defined in `pkg/core/interfaces.go` with an `IsEnabled` method to check if a feature is enabled.

The `Core` struct is updated to include this new `Features` struct, which is initialized in the `New` function.

Co-authored-by: google-labs-jules[bot] <161369871+google-labs-jules[bot]@users.noreply.github.com>

pkg/core/core.go

@@ -15,6 +15,7 @@ import (
 func New(opts ...Option) (*Core, error) {
 	c := &Core{
 		services: make(map[string]any),
+		Features: &Features{},
 	}
 	for _, o := range opts {
 		if err := o(c); err != nil {

pkg/core/interfaces.go

@@ -16,6 +16,21 @@ type Contract struct {
 	DontPanic      bool
 	DisableLogging bool
 }
+
+// Features provides a way to check if a feature is enabled.
+type Features struct {
+	Flags []string
+}
+
+// IsEnabled returns true if the given feature is enabled.
+func (f *Features) IsEnabled(feature string) bool {
+	for _, flag := range f.Flags {
+		if flag == feature {
+			return true
+		}
+	}
+	return false
+}
 type Option func(*Core) error
 type Message interface{}
 type Core struct {
@@ -23,6 +38,7 @@ type Core struct {
 	initErr        error
 	App            *application.App
 	assets         embed.FS
+	Features       *Features
 	serviceLock    bool
 	ipcMu          sync.RWMutex
 	ipcHandlers    []func(*Core, Message) error