fix(tmux): conditionally mark server running and add interactive bash helper

🤖 Generated with assistance of [OhMyOpenCode](https://github.com/code-yeongyu/oh-my-opencode)

src/create-runtime-tmux-config.ts

@@ -7,6 +7,12 @@ export function isTmuxIntegrationEnabled(
   return pluginConfig.tmux?.enabled ?? false
 }
 
+export function isInteractiveBashEnabled(
+  which: (binary: string) => string | null = Bun.which,
+): boolean {
+  return which("tmux") !== null
+}
+
 export function createRuntimeTmuxConfig(pluginConfig: { tmux?: OhMyOpenCodeConfig["tmux"] }): TmuxConfig {
   return TmuxConfigSchema.parse(pluginConfig.tmux ?? {})
 }