fix(launcher): create fresh sessions for new chats

[Edison-A-N]

Summary

• add a Launcher main-process API to create unique local chat session metadata
• expose the session creation IPC through preload and renderer types
• make New Chat create and activate a fresh chat-* channel instead of reopening main

Verification

• npm run build (packages/launcher)
• git diff --check

[vercel]

@Edison-A-N is attempting to deploy a commit to the Raphael's projects Team on Vercel.

A member of the Team first needs to authorize it.