docs: update README.md, hooks.md, and CHANGELOG for steer()/followUp() API

- Fix settings-selector descriptions to explain one-at-a-time vs all
- Update README.md message queuing section, settings example, and table
- Update hooks.md: hasPendingMessages, sendMessage options, triggerTurn example
- Add Theme/ThemeColor export and hasPendingMessages rename to CHANGELOG

packages/coding-agent/src/modes/interactive/components/settings-selector.ts

@@ -131,14 +131,16 @@ export class SettingsSelectorComponent extends Container {
 			{
 				id: "steering-mode",
 				label: "Steering mode",
-				description: "How to deliver steering messages (Enter while streaming)",
+				description:
+					"Enter while streaming queues steering messages. 'one-at-a-time': deliver one, wait for response. 'all': deliver all at once.",
 				currentValue: config.steeringMode,
 				values: ["one-at-a-time", "all"],
 			},
 			{
 				id: "follow-up-mode",
 				label: "Follow-up mode",
-				description: "How to deliver follow-up messages (queued until agent finishes)",
+				description:
+					"Alt+Enter queues follow-up messages until agent stops. 'one-at-a-time': deliver one, wait for response. 'all': deliver all at once.",
 				currentValue: config.followUpMode,
 				values: ["one-at-a-time", "all"],
 			},