Add upgrade command to CLI

src/cli/index.ts

@@ -264,4 +264,16 @@ $ true
 [0]`)
   })
 
+program
+  .command("upgrade")
+  .description("Upgrade sandlot to the latest version")
+  .action(async () => {
+    const result = await Bun.spawn(["bun", "install", "-g", "@because/sandlot@latest"], {
+      stdin: "inherit",
+      stdout: "inherit",
+      stderr: "inherit",
+    }).exited
+    process.exit(result)
+  })
+
 program.parse()