* fix(mcp): redact secrets in /mcp show replies
Prevent owner /mcp show from dumping raw headers/env credentials into
group chats. Mark MCP env values sensitive, restore redaction sentinels
on set so show→set cannot overwrite real secrets.
Fixes#103053
* test(mcp): e2e redaction of /mcp show secrets on live gateway
Spin up an ephemeral gateway process, chat.send /mcp show with live
credential-bearing config, and prove secrets never leave the reply path.
Also prove show→set sentinel restore on disk via chat and CLI.
08b6996cd5