Show session list by default when sessions exist

src/cli.ts

@@ -801,6 +801,18 @@ complete -c sandlot -n "__fish_seen_subcommand_from vm; and not __fish_seen_subc
 `)
   })
 
+// Default: show list if sessions exist, otherwise help
+const args = process.argv.slice(2)
+if (args.length === 0) {
+  try {
+    const root = await git.repoRoot()
+    const st = await state.load(root)
+    if (Object.keys(st.sessions).length > 0) {
+      process.argv.push("list")
+    }
+  } catch {}
+}
+
 program.parseAsync().catch((err) => {
   console.error(`✖ ${err.message ?? err}`)
   process.exit(1)