dsh-wsl-mail: Read-Only Email Viewing with himalaya/notmuch

`dsh-wsl-mail` is a DeepSeek Harness plugin that runs in WSL environments and provides agents with read-only email capabilities. It wraps `himalaya` and `notmuch` to offer email listing and search, but does not support sending or deleting messages. Users must configure the email tools themselves and should avoid storing passwords in plaintext in configuration files. Installation requires the `dsh plugin` command and a minimum DSH version of 0.1.2 or higher. Due to inconsistent version information, `package.json` should be treated as the authoritative source. For scenarios in which agents need to process email summaries or perform searches, this plugin provides a convenient integration solution.