[Desktop] Inter-session messages now render as a collapsed "Received message from …" row — please add a setting to show them expanded inline

## Summary

Since Claude Desktop **2.110.0** (rolled out around 2026-09-15), a message that one Code session sends to another (via `send_message` / `SendMessage`) is rendered in the receiving session's transcript as a **single collapsed row** — `Received message from ›` — and the message body is only visible after clicking into that row.

Previously the full message body appeared inline in the transcript, the same way a user message does.

Collapsed-by-default is a reasonable default. **The request is for a setting that lets people who want to read these messages see them expanded inline.**

## Why this matters

When several long-running sessions coordinate with each other, the human is effectively supervising that coordination. With the full text inline, I could skim what the sessions were telling each other and catch problems as they happened — a session relaying a wrong conclusion, a mis-attributed number, a false alarm.

With one collapsed row per message, these are easy to miss entirely. In practice I have stopped noticing inter-session messages at all. On a single recent day, messages exchanged between my sessions contained several factual errors (later corrected by the sessions themselves); with the new rendering, none of them were visible to me without clicking into each row one by one.

## Request

A user setting, defaulting to the current collapsed behavior, e.g.:

- **Show inter-session messages expanded** — render the full message body inline, like user messages.

A per-row expand/collapse affordance that remembers the last choice would also help.

## What I checked locally (no workaround available)

- The Code tab UI is loaded remotely (`assets-proxy.anthropic.com`), not from the local `app.asar`, so there is nothing local to adjust.
- The only local setting related to inter-session messages is `crossSessionInbound` (`accept` / `hold` / `refuse`), which controls **delivery**, not display.
- No display-related preference for this exists in `claude_desktop_config.json`, `config.json`, or the app's Local Storage / IndexedDB.

## Environment

- Claude Desktop 2.110.0
- Bundled Claude Code 2.1.271
- macOS 26.6.2 (Apple Silicon)

Start by investigating the remotely loaded Code tab UI at assets-proxy.anthropic.com, since the issue reports no relevant implementation in the local app.asar. Review crossSessionInbound and the listed claude_desktop_config.json, config.json, Local Storage, and IndexedDB locations to distinguish delivery from display settings. Done means a user setting can preserve collapsed messages by default while allowing inter-session message bodies to render expanded inline.

Written by the indexing model from the issue text.