feat(tui): Ctrl+o to expand/collapse tool call JSON

[lostmygithubaccount]

Problem

Tool calls in the Otto TUI show only a truncated 80-char summary. Tool call arguments are discarded entirely. Users have no way to inspect full tool call details.

Summary

Adds a global Ctrl+o toggle that expands/collapses tool call arguments and output inline, with pretty-printed JSON.

Collapsed (default)

  ⚙ create_artifact
  → {"artifact_id": "tooluse_ZeyXcpTdx4bR6c7TvQdIRd", "artifact_type": "react…  Ctrl+o to expand

Expanded (Ctrl+o)

  you
  build a simple demo application showing a counter

  otto
  I'll create a simple counter application for you.

  ⚙ create_artifact
  ╭─ output ─
  │ {
  │   "artifact_id": "tooluse_ZeyXcpTdx4bR6c7TvQdIRd",
  │   "artifact_type": "react",
  │   "artifact_url": "/otto/artifact/tooluse_ZeyXcpTdx4bR6c7TvQdIRd",
  │   "name": "Counter Demo",
  │   "runtime_uuid": "01991585-cdcd-7490-a5ae-c3107b3685d6",
  │   "status": "created"
  │ }
  ╰──
  Ctrl+o to collapse

  otto
  Created a simple counter application with three buttons:
  - Decrease: Subtracts 1 from the counter
  - Reset: Sets the counter back to 0
  - Increase: Adds 1 to the counter

Changes

• Add ToolCallData struct storing tool name, arguments JSON, and full output on Message
• Plumb arguments through StreamMsgKind::ToolCallStart (previously discarded)
• Change active_tool_call from Option<String> to Option<(String, String)> to hold name + args
• Add expand_tool_calls bool toggle on App, bound to Ctrl+o globally
• Add render_tool_call() with collapsed/expanded rendering using existing code-block style
• Update /help and docs with new keybinding

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