Add aict touch tool for updating file timestamps with XML output

[github-actions]

Description

Add aict touch as a companion to aict stat. It would update file atime/mtime via os.Chtimes and output the resulting timestamps in structured XML.

Use Case

AI agents processing files often need to mark files as "visited" or update timestamps as part of a workflow. Currently there's no structured way to do this via aict.

Proposed XML Output

<touch timestamp="1746123456" files="1">
  <file path="main.go" absolute="/project/main.go"
        atime="1746123456" atime_ago_s="0"
        mtime="1746123456" mtime_ago_s="0"
        created="false"/>
</touch>

Flags

Flag	Description
-t	Specify timestamp (Unix epoch or date string)
-a	Update atime only
-m	Update mtime only
-c	Do not create file if it does not exist

Note

This is a write operation on metadata (not file content), which may warrant discussion on whether it fits the project's read-focused scope.