Refactor: Update custom instructions for 'ask' mode (#3583)

This commit refines the custom instructions for the 'ask' mode. The changes aim to provide clearer guidance to the AI, emphasizing thoroughness in answering questions and caution against prematurely switching to code implementation.

Specifically, the instructions were updated as follows:

- Changed "Make sure to answer the user's questions" to "Always answer the user’s questions thoroughly"
- Changed "don't rush to switch to implementing code" to "do not switch to implementing code unless explicitly requested by the user"
- Changed "Include Mermaid diagrams if they help make your response clearer" to "Include Mermaid diagrams when they clarify your response"

These changes are reflected in both [`src/shared/modes.ts`](src/shared/modes.ts:80) and its corresponding snapshot file [`src/core/prompts/__tests__/__snapshots__/system.test.ts.snap`](src/core/prompts/__tests__/__snapshots__/system.test.ts.snap:5458).

src/core/prompts/__tests__/__snapshots__/system.test.ts.snap

@@ -5452,7 +5452,7 @@ Language Preference:
 You should always speak and think in the "en" language.
 
 Mode-specific Instructions:
-You can analyze code, explain concepts, and access external resources. Make sure to answer the user's questions and don't rush to switch to implementing code. Include Mermaid diagrams if they help make your response clearer.
+You can analyze code, explain concepts, and access external resources. Always answer the user’s questions thoroughly, and do not switch to implementing code unless explicitly requested by the user. Include Mermaid diagrams when they clarify your response.
 
 Rules:
 # Rules from .clinerules-ask:

src/shared/modes.ts

@@ -75,7 +75,7 @@ export const modes: readonly ModeConfig[] = [
 			"You are Roo, a knowledgeable technical assistant focused on answering questions and providing information about software development, technology, and related topics.",
 		groups: ["read", "browser", "mcp"],
 		customInstructions:
-			"You can analyze code, explain concepts, and access external resources. Make sure to answer the user's questions and don't rush to switch to implementing code. Include Mermaid diagrams if they help make your response clearer.",
+			"You can analyze code, explain concepts, and access external resources. Always answer the user’s questions thoroughly, and do not switch to implementing code unless explicitly requested by the user. Include Mermaid diagrams when they clarify your response.",
 	},
 	{
 		slug: "debug",