docs: add MCP Server to getting started page and homepage (#8)

Adds the
[commit-check-mcp](https://github.com/commit-check/commit-check-mcp) MCP
server to the site, covering:

### Changes

**Getting Started page** — Added a 4th grid card for the MCP Server,
targeting AI coding agents (Claude Code, Cursor, Copilot, etc.).

**Homepage** — Updated the "Works Everywhere" card description to
include MCP server. Added a new Quick Start tab with an example MCP
config snippet.

### Why

The `commit-check-mcp` package is a mature part of the commit-check
ecosystem with a dedicated repo and PyPI package. It was missing from
the docs despite being listed under the org repos. This makes it
discoverable to users looking for AI-agent-friendly commit validation.

Author: shenxianpeng

docs/getting-started.md

@@ -38,4 +38,14 @@ Select the method that best fits your development workflow:
 
     [Get started with CLI →](https://commit-check.github.io/commit-check/){ .md-button .md-button--primary }
 
+- :material-robot: **MCP Server**
+
+    ---
+
+    MCP server exposing commit-check validations as structured tools for AI coding agents
+
+    **Perfect for:** Claude Code, Cursor, Copilot & any MCP-compatible AI agent
+
+    [Get started with MCP →](https://github.com/commit-check/commit-check-mcp){ .md-button .md-button--primary }
+
 </div>

docs/index.md

@@ -30,7 +30,7 @@ title: Commit Check
 
     ---
 
-    GitHub Actions, pre-commit hooks, or the command line — integrate Commit Check anywhere your code lives.
+    GitHub Actions, pre-commit hooks, command line, or MCP server — integrate Commit Check anywhere your code lives.
 
 </div>
 
@@ -154,6 +154,25 @@ title: Commit Check
     # And more...
     ```
 
+=== "MCP Server"
+
+    Add to your AI coding agent's MCP config:
+
+    ```json
+    {
+      "mcpServers": {
+        "commit-check": {
+          "command": "uvx",
+          "args": ["commit-check-mcp"]
+        }
+      }
+    }
+    ```
+
+    Then your agent can validate commit messages, branch names, author info, and more with structured results.
+
+    [Learn more about MCP →](https://github.com/commit-check/commit-check-mcp)
+
 ---
 
 <div class="community-section" markdown>