feat(coding-agent): added auto-backgrounding for long bash jobs to avoid blocking

- Added bash.autoBackground.enabled and bash.autoBackground.thresholdMs settings with defaults for background job behavior.
- Added auto-backgrounding support for long foreground bash commands with managed job state and timeout threshold.
- Updated bash prompts, job-protocol messages, and tool activation checks to use async and auto-background support.
- Added background bash completion integration with AsyncJobManager and end-to-end tests for short/long auto-background scenarios.

packages/coding-agent/src/task/executor.ts

@@ -435,7 +435,11 @@ function createSubagentSettings(baseSettings: Settings): Settings {
 	for (const key of Object.keys(SETTINGS_SCHEMA) as SettingPath[]) {
 		snapshot[key] = baseSettings.get(key);
 	}
-	return Settings.isolated({ ...snapshot, "async.enabled": false });
+	return Settings.isolated({
+		...snapshot,
+		"async.enabled": false,
+		"bash.autoBackground.enabled": false,
+	});
 }
 
 /**