Add option to disable timing info (Cooked/Baked for X)

Problem

After each response, Claude Code displays timing information like "Cooked for 1m 6s" or "Baked for 1m 35s". There is no option to disable this.

Current behavior

• Timing info always appears after responses
• Cannot be disabled without losing other useful metrics
• Related to #6308 and #5959 but those focus on token usage, not disabling timing

Requested feature

Add a setting to disable timing display, e.g.:

{
  "showTimingInfo": false
}

Or environment variable:

CLAUDE_CODE_SHOW_TIMING=false

Why this matters

• Clutters the terminal output
• Not useful for all users
• Should be opt-in or at least opt-out

Workaround attempted

• Removing statusLine from settings.json - doesn't help
• No verbose setting affects this

Thanks!