Hooks can render custom status (#385)

* Add ctx.ui.setStatus(key, text) API for hooks to display status in footer

- Add setStatus to HookUIContext interface
- Implement in interactive mode (FooterComponent)
- Implement in RPC mode (fire-and-forget)
- Add no-op implementations for headless contexts
- Multiple statuses displayed on single line, sorted by key
- Supports ANSI styling (hooks handle their own colors)

* Remove setStatus from changelog for now

* Fix hook status API to follow TUI rules

- Sanitize status text: replace newlines, tabs, carriage returns with spaces
- Truncate combined status line to terminal width using truncateToWidth
- Update JSDoc to document sanitization and truncation behavior
- Remove unused createHookUIContext method
- Add missing setStatus to test mock

* Add setStatus to changelog

* Use dim ellipsis for hook status truncation for consistency with footer style

---------

Co-authored-by: Mario Zechner <badlogicgames@gmail.com>

packages/coding-agent/src/modes/rpc/rpc-mode.ts

@@ -119,6 +119,17 @@ export async function runRpcMode(session: AgentSession): Promise<never> {
 			} as RpcHookUIRequest);
 		},
 
+		setStatus(key: string, text: string | undefined): void {
+			// Fire and forget - no response needed
+			output({
+				type: "hook_ui_request",
+				id: crypto.randomUUID(),
+				method: "setStatus",
+				statusKey: key,
+				statusText: text,
+			} as RpcHookUIRequest);
+		},
+
 		async custom() {
 			// Custom UI not supported in RPC mode
 			return undefined as never;