add root README with marketplace install and plugin catalog

Follows cc-foundry pattern: one-liner, marketplace install
command, per-plugin problem/solution description with install
snippet. Kensai entry covers the four-phase pipeline and
links to the published npm package.

Author: xobotyi

README.md

@@ -0,0 +1,38 @@
+# yatai
+
+Gaijin Entertainment's plugin marketplace for AI coding tools.
+
+Plugins built for internal workflows — code review pipelines, development automation, quality enforcement — published
+for anyone to use.
+
+## Installation
+
+Add the marketplace, then install any plugin:
+
+```
+/plugin marketplace add GaijinEntertainment/yatai
+/plugin install <plugin-name>
+```
+
+## Plugins
+
+### kensai
+
+Multi-agent code review with adversarial falsification. Parallel reviewers surface issues; a prover applies
+falsification gates to filter false positives. Orchestrated by a stateful MCP server
+([`@gaijin/kensai-review-mcp`](https://www.npmjs.com/package/@gaijin/kensai-review-mcp)).
+
+Requires Node.js 26+ and agent teams (`CLAUDE_CODE_EXPERIMENTAL_AGENT_TEAMS=1`).
+
+```
+/plugin install kensai
+```
+
+## Requirements
+
+- [Claude Code](https://claude.com/claude-code) with plugin marketplace support
+- Node.js 26+ (for MCP server plugins)
+
+## License
+
+MIT

claude/kensai/mcp/review/README.md

@@ -0,0 +1,30 @@
+# @gaijin/kensai-review-mcp
+
+Stateful MCP server for the [kensai](https://github.com/GaijinEntertainment/yatai/tree/main/claude/kensai) multi-agent
+code review pipeline.
+
+Provides 24 tools across 4 toolsets (session lifecycle, filesystem, git, findings) with phase-enforced state machine,
+paginated context delivery, and scoped filesystem access.
+
+## Usage
+
+This package is consumed as an MCP server via the kensai Claude Code plugin. Install the plugin:
+
+```
+/plugin marketplace add GaijinEntertainment/yatai
+/plugin install kensai
+```
+
+Or run standalone:
+
+```
+npx @gaijin/kensai-review-mcp
+```
+
+## Requirements
+
+- Node.js 26+
+
+## License
+
+MIT

claude/kensai/mcp/review/src/index.ts

@@ -1,3 +1,4 @@
+#!/usr/bin/env node
 import { McpServer } from "@modelcontextprotocol/sdk/server/mcp.js";
 import { StdioServerTransport } from "@modelcontextprotocol/sdk/server/stdio.js";