feat: New() constructors for Config, Fs + simplify contract.go init

Config.New() initialises ConfigOptions.
Fs.New(root) sets sandbox root.
ErrorLog uses Default() fallback — no explicit init needed.
contract.go uses constructors instead of struct literals.

All tests green.

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

config.go

@@ -48,6 +48,15 @@ type Config struct {
 	mu sync.RWMutex
 }
 
+// New initialises a Config with empty settings and features.
+//
+//	cfg := (&core.Config{}).New()
+func (e *Config) New() *Config {
+	e.ConfigOptions = &ConfigOptions{}
+	e.ConfigOptions.init()
+	return e
+}
+
 // Set stores a configuration value by key.
 func (e *Config) Set(key string, val any) {
 	e.mu.Lock()

contract.go

@@ -93,10 +93,10 @@ func New(opts ...CoreOption) Result {
 		app:      &App{},
 		data:     &Data{},
 		drive:    &Drive{},
-		fs:       &Fs{root: "/"},
-		config:   &Config{ConfigOptions: &ConfigOptions{}},
+		fs:       (&Fs{}).New("/"),
+		config:   (&Config{}).New(),
 		error:    &ErrorPanic{},
-		log:      &ErrorLog{log: Default()},
+		log:      &ErrorLog{},
 		lock:     &Lock{},
 		ipc:      &Ipc{},
 		info:     systemInfo,

fs.go

@@ -13,6 +13,18 @@ type Fs struct {
 	root string
 }
 
+// New initialises an Fs with the given root directory.
+// Root "/" means unrestricted access. Empty root defaults to "/".
+//
+//	fs := (&core.Fs{}).New("/")
+func (m *Fs) New(root string) *Fs {
+	if root == "" {
+		root = "/"
+	}
+	m.root = root
+	return m
+}
+
 // path sanitises and returns the full path.
 // Absolute paths are sandboxed under root (unless root is "/").
 // Empty root defaults to "/" — the zero value of Fs is usable.

ipc.go

@@ -12,6 +12,8 @@ import (
 )
 
 // Ipc holds IPC dispatch data.
+//
+//	ipc := (&core.Ipc{}).New()
 type Ipc struct {
 	ipcMu       sync.RWMutex
 	ipcHandlers []func(*Core, Message) Result