feat: add Claude Code plugin with vz skill

Plugin structure for /plugin marketplace add gpu-cli/vz:
- .claude-plugin/plugin.json — plugin manifest (v0.3.0)
- .claude-plugin/marketplace.json — marketplace catalog
- skills/vz/SKILL.md — skill that routes Linux commands through vz run

The skill auto-triggers when a project has vz.json or the user needs
Linux-specific execution. Covers vz run, vz init, vz status, vz logs,
interactive mode, setup vs runtime commands, and common error patterns.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: lightsofapollo

.claude-plugin/marketplace.json

@@ -0,0 +1,15 @@
+{
+  "name": "gpu-cli",
+  "owner": {
+    "name": "gpu-cli"
+  },
+  "plugins": [
+    {
+      "name": "vz",
+      "source": {
+        "source": "github",
+        "repo": "gpu-cli/vz"
+      }
+    }
+  ]
+}

.claude-plugin/plugin.json

@@ -0,0 +1,10 @@
+{
+  "name": "vz",
+  "description": "Run commands in instant Linux VMs on macOS via vz",
+  "version": "0.3.0",
+  "author": {
+    "name": "gpu-cli"
+  },
+  "repository": "https://github.com/gpu-cli/vz",
+  "license": "MIT"
+}

skills/vz/SKILL.md

@@ -0,0 +1,98 @@
+---
+name: vz
+description: >
+  Run commands in instant Linux VMs on macOS via vz. Use when the user needs
+  to: (1) compile or test code for Linux (cross-compile, Linux-only deps),
+  (2) run Linux-specific tools (apt-get, systemd, docker-in-VM),
+  (3) execute commands in an isolated Linux environment,
+  (4) work on a project that has a vz.json file.
+  TRIGGER when: project contains vz.json, user says "run in Linux",
+  "test on Linux", "compile for Linux", "vz run", or needs Linux-only behavior.
+  DO NOT TRIGGER when: commands work fine on macOS natively.
+---
+
+# vz — Linux VM execution
+
+Run commands inside a lightweight Linux VM on macOS via Apple's Virtualization.framework.
+The VM boots in ~3s, mounts the project directory via VirtioFS, and persists across runs.
+
+## Detection
+
+Check if the project has a `vz.json` in the working directory or parents. If it does,
+Linux commands should go through `vz run` instead of running locally.
+
+## Commands
+
+### Run a command
+
+```bash
+vz run <command...>
+```
+
+Output streams in real-time. Exit code propagates. Environment variables from
+`vz.json` are injected automatically (PATH, HOME, CARGO_TARGET_DIR, etc.).
+
+Examples:
+```bash
+vz run cargo build
+vz run cargo test
+vz run make -j4
+vz run apt-get install -y libssl-dev  # only works during setup, not ad-hoc
+vz run python3 script.py
+```
+
+### Interactive shell
+
+```bash
+vz run -i bash
+```
+
+Opens a PTY-backed interactive session. Use for debugging, exploring the
+VM filesystem, or running interactive tools.
+
+### Project setup
+
+```bash
+vz init                    # generate vz.json (auto-detects Rust/Node/Python/Go)
+vz init --template rust    # force a specific template
+vz init --image debian:12  # override base image
+```
+
+### Lifecycle
+
+```bash
+vz status       # show daemon/VM state, project, mounts
+vz stop         # stop the VM (persists disk, next run reboots)
+vz run --fresh  # destroy VM + re-run setup from scratch
+vz logs         # show daemon logs
+vz logs -f      # follow daemon logs
+```
+
+## When to use vz run vs local execution
+
+Use `vz run` when:
+- The command needs Linux (cargo build for linux targets, apt-get, Linux syscalls)
+- The project has a `vz.json`
+- The user explicitly asks to run in Linux or in a VM
+
+Use local execution when:
+- The command works on macOS natively (git, formatting, linting)
+- No `vz.json` exists and user hasn't asked for Linux
+
+## Setup commands vs runtime commands
+
+`vz.json` has a `setup` array — these run once on first boot and are cached by hash.
+Do NOT put one-off commands in setup. Instead:
+- **Setup**: package installs, toolchain setup (apt-get, rustup, npm install -g)
+- **Runtime**: build, test, run commands (cargo build, npm test)
+
+If the user needs a new package installed, suggest adding it to the `setup` array
+in `vz.json` and running `vz run --fresh` to re-provision.
+
+## Error patterns
+
+- **"no vz.json found"** — suggest `vz init`
+- **"getcwd() failed"** — harmless kernel warning, ignore it
+- **Setup reruns every time** — setup command may be failing silently; check with `vz run --fresh` and watch output
+- **"daemon startup timed out"** — stale lock file; `vz stop` then retry
+- **Command not found in VM** — tool not in setup commands; add to `vz.json` setup array