Add an always-expand-all inspection mode in the desktop app thread UI

Problem

In the desktop app, even with Thread detail = Steps with code output, a lot of the useful inspection surface is still collapsed by default.

That makes it hard to supervise the agent live and steer it while it works, because I still have to keep manually expanding:

• edit/code-change events
• diffs/snippets tied to edits
• tool result details
• some step details that matter for auditing what changed

The current setting helps with command visibility, but it does not provide a true fully expanded inspection mode.

There is already a useful diff sidebar for inspecting edits, but it is not the same as a fully expanded working transcript.

The sidebar is good for reviewing resulting changes. What is still missing is a mode where the main thread itself stays expanded, so I can supervise the agent live in one place while it works, including step details, tool output, and edit context, without needing to bounce between collapsed thread items and the sidebar.

What I want

Please add a desktop-app setting such as:

• Always expand all thread details
• or Verbose / inspection mode

When enabled, keep the relevant thread items expanded by default, especially:

• code edit steps
• edit diffs/snippets
• tool outputs
• step details

Why this matters

For users who actively supervise the agent, collapsed steps add a lot of friction.

I want to be able to scan the thread with my eyes and immediately see what the agent is doing, what changed, and whether I should steer it, without repeatedly clicking open dozens of collapsed items.

This is especially useful for:

• reviewing edits as they happen
• catching wrong assumptions early
• auditing tool usage
• steering long-running coding sessions

Related issues

This feels related to, but not the same as:

• #4550 — configurable or disable-able command folding / truncation in the CLI/TUI
• #2925 — transcript collapsing controls in the CLI/TUI

My request here is specifically about the desktop app thread UI and having a mode that keeps the whole working transcript meaningfully expanded for live supervision.