feat: make bash command display length adapt to terminal width

[li0near]

Summary

Bash commands in the tools activity line were hardcoded to truncate at 30 characters, which often cuts off useful context (e.g., git commit -m "Fix auth... instead of the full command).

This PR:

• Makes truncation dynamic based on terminal width ($COLUMNS), so wider terminals show more of the command
• Adds a display.toolTargetMaxLength config option for explicit control:
  • 0 (default): auto-detect from terminal width
  • Any positive number: use as the max character length
• Updates the path truncation in tools-line.ts to also respect this config

Config example

{
  "display": {
    "toolTargetMaxLength": 80
  }
}

Or set to 0 (default) to auto-fit to terminal width.

Test plan

• All 576 existing tests pass
• Updated the bash truncation test to verify terminal-width-based behavior
• Build passes cleanly with tsc

[jarrodwatts]

Thanks for the PR. This is superseded by #571, which merged configurable tool-name length and safer render-time wrapping. This branch also expands transcript-derived Bash targets using env-derived width and exposes longer untrusted command text on the tools line, which is too risky for the hot statusline path.