Add Codex plugin manifest and setup skill

Author: ndycode

.codex-plugin/plugin.json

@@ -0,0 +1,6 @@
+{
+  "name": "codex-multi-auth",
+  "version": "1.2.1",
+  "description": "Install and operate codex-multi-auth for the official @openai/codex CLI with multi-account OAuth rotation, switching, health checks, and recovery tools.",
+  "skills": "./skills/"
+}

skills/codex-auth-setup/SKILL.md

@@ -0,0 +1,73 @@
+---
+name: codex-auth-setup
+description: Install or refresh codex-multi-auth for the official Codex CLI, run first login, and verify account health and routing.
+---
+
+# codex-auth-setup
+
+Use this skill when the user wants to install, reinstall, upgrade, or troubleshoot `codex-multi-auth` for the official `@openai/codex` CLI.
+
+## Install
+
+```bash
+npm i -g @openai/codex
+npm i -g codex-multi-auth
+```
+
+If the old scoped prerelease package is still installed:
+
+```bash
+npm uninstall -g @ndycode/codex-multi-auth
+npm i -g codex-multi-auth
+```
+
+## First login
+
+```bash
+codex auth login
+```
+
+Default flow:
+
+1. Open the account menu.
+2. Choose the browser-first OAuth path.
+3. Complete the official OAuth flow.
+4. Return to the terminal and confirm the account was saved.
+
+## Verify health and routing
+
+```bash
+codex auth status
+codex auth list
+codex auth check
+codex auth forecast --live
+```
+
+Use these next when managing multiple accounts:
+
+```bash
+codex auth switch 2
+codex auth verify-flagged
+codex auth doctor --fix
+```
+
+## Alternate login paths
+
+Use these when browser launch is blocked or the shell is headless:
+
+```bash
+codex auth login --manual
+CODEX_AUTH_NO_BROWSER=1 codex auth login
+```
+
+## Troubleshooting
+
+- Run `where codex` if `codex auth` is not recognized.
+- Free port `1455` and retry if the OAuth callback server cannot bind.
+- Re-run `codex auth login` if the active account is stale or the wrong account was selected.
+- Use `codex auth doctor --fix` followed by `codex auth check` for a fast recovery loop.
+- See `docs/getting-started.md`, `docs/configuration.md`, `docs/troubleshooting.md`, and `docs/reference/commands.md` for the full command and config docs.
+
+## Usage boundaries
+
+This project is for personal development use. For production or commercial workloads, use the OpenAI Platform API.