dsh-obsidian: Enable dsh to directly read and write local Obsidian vaults

dsh-obsidian is an MIT-licensed plugin for DeepSeek Harness (dsh) designed to enable the dsh agent to directly interact with a local Obsidian vault without relying on an MCP server, OAuth, or REST APIs. It leverages `node:fs` to treat the vault as a Markdown file system, parsing frontmatter and wikilinks, and mounts 12 `obsidian_*` tools. Features include searching, reading, writing, appending, moving, deleting (moving to trash), querying backlinks, tag statistics, and managing frontmatter properties for notes. The plugin supports explicit path configuration via `vaultPath` or automatic detection based on a provided base path.