fix(plugin): move the Claude Code plugin into plugins/codeman so an install no longer runs npm install

With the repo root as the plugin root, `claude plugin install codeman@codeman`
copied the whole checkout into its cache and, because that root carries a
package.json, ran an npm install there: 832 MB, 511 packages and this repo's
postinstall build on every installer's machine (measured from a clean worktree
of the previous commit). A plugin root must be a directory without one.

The plugin is now `plugins/codeman/`: its manifest, a README, and a MIRROR of
`skills/codeman/`. A mirror rather than a symlink because the install copies
the plugin directory and a link pointing outside it would dangle; a mirror
rather than the source because every install path, injector and doc already
names `skills/codeman/`. `scripts/sync-plugin.mjs` (replacing
sync-plugin-version.mjs) mirrors the skill and syncs both manifest versions
inside `version-packages`; `test/plugin-manifest.test.ts` pins byte-identity,
the versions, the absence of a package.json in the plugin root and that the
repo root `.claude-plugin/` holds only the marketplace manifest.

`claude plugin validate --strict` now passes for both the plugin and the repo
root. Install commands are unchanged.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

CLAUDE.md

@@ -6,7 +6,7 @@ This file provides guidance to Claude Code (claude.ai/code) when working with co
 >
 > **This file is in `.prettierignore` on purpose.** Prettier's markdown printer escapes underscores inside the glob-heavy paths used throughout (`agent-*.jsonl` became `agent-\_.jsonl`, collapsing backtick spans and corrupting a whole paragraph). Do not remove the ignore entry, and do not run `prettier --write` on it.
 >
-> **Repo root is kept short on purpose** (the README sits below the file listing on GitHub). Config lives in `config/` (`eslint.config.js`, `knip.json`, the vitest configs), Prettier's config is the `"prettier"` key in `package.json`, and `SECURITY.md` is under `.github/`. Root-only files are the ones tools genuinely require there: `CLAUDE.md` + `AGENTS.md` (loaded from the root by Claude Code / Codex), `CHANGELOG.md` (changesets writes it next to `package.json`), `tsconfig.json`, `.editorconfig`, `.nvmrc`/`.npmrc`, `.prettierignore` (resolved relative to cwd), `LICENSE` (GitHub detection), `.dockerignore` (the build context is the repo root, so Docker resolves it there and nowhere else) and `install.sh` (its raw URL is the published install one-liner). `.claude-plugin/` (`plugin.json` + `marketplace.json`) is root-only for the same reason: `/plugin marketplace add Ark0N/Codeman` reads it from the repo root and nowhere else, which makes the repo its own plugin marketplace with the repo itself (`source: "./"`) as the one plugin, whose one component is `skills/codeman/`. Both manifests carry `package.json`'s version, synced by `scripts/sync-plugin-version.mjs` inside `version-packages` and pinned by `test/plugin-manifest.test.ts`, which also refuses any other plugin component (`commands/`, `agents/`, `hooks/`, `.mcp.json`, `settings.json`) appearing at the root, since an install would silently ship it. Don't relocate those.
+> **Repo root is kept short on purpose** (the README sits below the file listing on GitHub). Config lives in `config/` (`eslint.config.js`, `knip.json`, the vitest configs), Prettier's config is the `"prettier"` key in `package.json`, and `SECURITY.md` is under `.github/`. Root-only files are the ones tools genuinely require there: `CLAUDE.md` + `AGENTS.md` (loaded from the root by Claude Code / Codex), `CHANGELOG.md` (changesets writes it next to `package.json`), `tsconfig.json`, `.editorconfig`, `.nvmrc`/`.npmrc`, `.prettierignore` (resolved relative to cwd), `LICENSE` (GitHub detection), `.dockerignore` (the build context is the repo root, so Docker resolves it there and nowhere else) and `install.sh` (its raw URL is the published install one-liner). `.claude-plugin/marketplace.json` is root-only for the same reason: `/plugin marketplace add Ark0N/Codeman` reads it from the repo root and nowhere else, which makes the repo its own plugin marketplace. The one plugin it lists is `plugins/codeman/` (manifest + README + a MIRROR of `skills/codeman/`), and ⚠️ the plugin is a small separate directory on purpose: `claude plugin install` copies the plugin root into its cache, and a plugin root that carries a `package.json` gets an **npm install** at install time (measured with the repo root as plugin root: 832 MB, 511 packages and this repo's postinstall on every installer's machine), while a symlink to `skills/codeman` would dangle in the copy. `skills/codeman/` stays the single source; `scripts/sync-plugin.mjs` mirrors it and writes `package.json`'s version into both manifests inside `version-packages`, and `test/plugin-manifest.test.ts` pins the byte-identity, the versions, the absence of a `package.json` in the plugin root and that no other component (`commands/`, `agents/`, `hooks/`, `.mcp.json`, `settings.json`) rides along. Don't relocate those.
 
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