feat: reastructure and create commands

cmd/invoicer/cmd.go

@@ -0,0 +1,17 @@
+package main
+
+type cmd struct {
+	cmd    func(any)
+	config any
+}
+
+func (c *cmd) Run() {
+	c.cmd(c.config)
+}
+
+var commands = map[string]cmd{
+	"config": {
+		config,
+		nil,
+	},
+}