feat: add go backend skeleton

internal/app/config.go

@@ -0,0 +1,22 @@
+package app
+
+import (
+	"os"
+	"path/filepath"
+)
+
+type Config struct {
+	CodexHome string
+	HTTPAddr  string
+}
+
+func DefaultConfig() Config {
+	home, err := os.UserHomeDir()
+	if err != nil {
+		home = "."
+	}
+	return Config{
+		CodexHome: filepath.Join(home, ".codex"),
+		HTTPAddr:  "127.0.0.1:18083",
+	}
+}