fix(coding-agent/slash-commands): fixed slash command shutdown handler return contract

- Updated the TUI shutdown slash command handler to return a `SlashCommandResult` instead of `void`.
- Returned `commandConsumed()` after clearing the editor and invoking runtime shutdown.
- Imported `SkillPromptDetails` as a type in the input controller message imports.

packages/coding-agent/src/modes/controllers/input-controller.ts

@@ -8,7 +8,7 @@ import { createPromptActionAutocompleteProvider } from "../../modes/prompt-actio
 import { theme } from "../../modes/theme/theme";
 import type { InteractiveModeContext } from "../../modes/types";
 import type { AgentSessionEvent } from "../../session/agent-session";
-import { SKILL_PROMPT_MESSAGE_TYPE } from "../../session/messages";
+import { SKILL_PROMPT_MESSAGE_TYPE, type SkillPromptDetails } from "../../session/messages";
 import { executeBuiltinSlashCommand } from "../../slash-commands/builtin-registry";
 import { copyToClipboard, readImageFromClipboard } from "../../utils/clipboard";
 import { getEditorCommand, openInEditor } from "../../utils/external-editor";

packages/coding-agent/src/slash-commands/builtin-registry.ts

@@ -51,9 +51,10 @@ function refreshStatusLine(ctx: InteractiveModeContext): void {
 	ctx.ui.requestRender();
 }
 
-const shutdownHandlerTui = (_command: ParsedSlashCommand, runtime: TuiSlashCommandRuntime): void => {
+const shutdownHandlerTui = (_command: ParsedSlashCommand, runtime: TuiSlashCommandRuntime): SlashCommandResult => {
 	runtime.ctx.editor.setText("");
 	void runtime.ctx.shutdown();
+	return commandConsumed();
 };
 
 const BUILTIN_SLASH_COMMAND_REGISTRY: ReadonlyArray<SlashCommandSpec> = [