Add --max-depth flag to grep for recursive search depth limiting

[github-actions]

Description

aict grep -r currently walks the entire directory tree with no depth limit. On large monorepos this produces excessive output and is slow.

Proposed Solution

Add --max-depth N flag mirroring find's -maxdepth behavior.

Usage:

aict grep "func" . -r --max-depth 2

This would search only 2 levels deep from the search root.

XML Output Change

Add max_depth attribute to the root <grep> element:

<grep pattern="func" recursive="true" max_depth="2" ...>

Motivation

• Consistency with find tool which already has -maxdepth
• Faster targeted searches in large codebases
• Reduces token count for AI agents that only need shallow results

Related

• tools/grep/grep.go searchDirectory function
• tools/find/find.go MaxDepth implementation (reference)