Add optional mode suggestions to follow-up questions

[mrubens]

Let the LLM suggest answers that also switch modes to save you a round trip

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Important

This PR adds mode-switching capabilities to follow-up question suggestions, allowing users to switch modes directly from the suggestion, with backend and frontend updates to support this feature.

• Behavior:
  • Adds optional mode attribute to <suggest> tags in ask_followup_question to switch modes when selected.
  • Mode change is automatic and indicated by a visual badge.
• Backend:
  • Updates askFollowupQuestionTool in askFollowupQuestionTool.ts to parse and handle mode attributes.
  • Adds tests in askFollowupQuestionTool.spec.ts to verify parsing of suggestions with and without mode attributes.
• Frontend:
  • Updates FollowUpSuggest.tsx to handle mode attribute, sending mode switch messages via vscode.postMessage.
  • Displays mode badge on suggestions with a mode attribute.

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[delve-auditor]

✅ No security or compliance issues detected. Reviewed everything up to 5cb527c.

Security Overview

• 🔎 Scanned files: 17 changed file(s)

Detected Code Changes

Change Type	Relevant files
Enhancement	► askFollowupQuestionTool.ts     Add optional mode suggestions support ► CustomModesManager.ts     Update YAML string handling ► FollowUpSuggest.tsx     Add mode switching UI for suggestions
Configuration changes	► package.json     Update version from 3.22.2 to 3.22.1

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[jr]

I find it hard to predict when the modes will actually use this, but it's nice when they do.