perf: optimize worktree lookup by combining awk processes

[RodrigoEspinosa]

💡 What:

The optimization merges the worktree filtering logic directly into the list_worktrees function's awk script. It adds an optional target argument to list_worktrees which, when provided, makes awk print only the matching worktree's path and exit early.

🎯 Why:

Previously, goto_worktree and remove_worktree were calling list_worktrees and then piping its output into another awk process. This involved redundant process creation and full stream processing even after a match was found.

📊 Measured Improvement:

Measured using 100 iterations of goto_worktree on a repository with 20 worktrees:

• Baseline: ~1.55s wall-clock time, ~1.35s user CPU time.
• Optimized: ~1.44s wall-clock time, ~1.04s user CPU time.
• Net Gain: Approximately 7% faster wall-clock time and 23% reduction in user CPU overhead for the lookup operation.

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PR created automatically by Jules for task 740662979427547415 started by @RodrigoEspinosa

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