Bash tool: show elapsed time instead of timeout parameter on completion

Problem

When a Bash tool call completes successfully, the UI displays the configured timeout parameter (e.g., (timeout 5m)) rather than the actual elapsed time.

This is misleading — it looks like the command timed out, when in fact it completed normally within the limit.

Example: A plan review command completes in ~3 minutes. The UI shows:

Bash(uvx ... agent-loop plan review ...)
  [INFO] Created plan review: .../review.md
  (timeout 5m)

A user reading this naturally interprets (timeout 5m) as "the command timed out after 5 minutes," which creates confusion about whether the results are valid.

Proposed behavior

| Scenario | Current display | Proposed display |
|---|---|---|
| Command completes | (timeout 5m) | (2m 34s) |
| Command times out | (timeout 5m) | (timed out after 5m) |

• On successful completion: show elapsed wall-clock time (e.g., (2m 34s))
• On actual timeout: show an explicit timeout message (e.g., (timed out after 5m))

This removes ambiguity and gives useful feedback about command performance.