[FEATURE] Add "chat" or "discuss" mode alongside "plan" mode

Preflight Checklist

• [x] I have searched existing requests and this feature hasn't been requested yet
• [x] This is a single feature request (not multiple features)

Problem Statement

When exploring a codebase, discussing architecture, or trying to understand existing code, I want to have a conversation with Claude without it suggesting code changes or edits.

Currently I have to explicitly write "don't write code, just discuss" in every prompt to prevent Claude from jumping into implementation mode.

Proposed Solution

Add a "chat" or "discuss" mode similar to how "plan" mode works.

In this mode Claude would:

• Read and analyze code normally
• Answer questions about the codebase
• Discuss architecture and design patterns
• Compare different approaches
• NOT suggest code edits or write new code

Alternative Solutions

Currently I work around this by adding "don't write code, just discuss" to every prompt. It works but feels repetitive and clutters the conversation.

Priority

Low - Nice to have

Feature Category

CLI commands and flags

Use Case Example

1. I open a new microservices project I'm unfamiliar with
2. I want to understand how services communicate
3. I run claude --chat or type /chat to enter discussion mode
4. I ask "how does auth service talk to user service?"
5. Claude explains the architecture without suggesting changes
6. When ready to code, I switch back to normal mode

Additional Context

This would make Claude Code more useful for onboarding, code review discussions, and architectural planning sessions.