ui: gate /prompt command on the conversation tool policy

The slash command's availability now follows the same rule as the
agentic flow instead of the global capability check, so it disables
itself when the conversation's policy leaves no usable MCP server.

Assisted-by: pi

tools/ui/src/lib/components/app/chat/ChatForm/ChatForm.svelte

@@ -23,7 +23,8 @@
 		FileExtensionText,
 		KeyboardKey,
 		MimeTypeText,
-		SpecialFileType
+		SpecialFileType,
+		ToolSource
 	} from '$lib/enums';
 	import { useChatFormPickers } from '$lib/hooks/use-chat-form-pickers.svelte';
 	import {
@@ -153,7 +154,17 @@
 		getShowModelSelector: () => showModelSelector,
 		getValue: () => value,
 		hasCwdTools: () => conversationsStore.preferences.hasEnabledCwdTools(),
-		hasPrompts: () => mcpStore.hasPromptsCapability(),
+		// policy-aware, same rule as the agentic flow: MCP category on and at
+		// least one globally-enabled server whose group key is not disabled
+		hasPrompts: () => {
+			const prefs = conversationsStore.preferences;
+
+			if (!prefs.isCategoryEnabled(ToolSource.MCP)) return false;
+
+			return mcpStore
+				.getServers()
+				.some((s) => s.enabled && prefs.isServerToolsEnabled(s.id) && s.url.trim());
+		},
 		openModelSelector: () => chatFormActionsRef?.openModelSelector(),
 		setCaretOffset: (offset) => inputRef?.setCaretOffset(offset),
 		setValue: (v) => {