feat: add Claude Code CLI support (#1111)

Added support for installing clasp as a Claude Code extension.
- Created `.claude-plugin/plugin.json` for plugin-based installation.
- Created `claude-mcp.json` for manual MCP configuration.
- Updated README.md with installation instructions.

Co-authored-by: google-labs-jules[bot] <161369871+google-labs-jules[bot]@users.noreply.github.com>

Author: Zircoz

.claude-plugin/plugin.json

@@ -0,0 +1,11 @@
+{
+  "name": "clasp",
+  "version": "1.0.0",
+  "description": "Develop Apps Script projects locally using clasp",
+  "mcpServers": {
+    "clasp": {
+      "command": "npx",
+      "args": ["-y", "@google/clasp", "mcp"]
+    }
+  }
+}

README.md

@@ -78,6 +78,32 @@ This makes clasp available as an MCP server in Gemini CLI.
 
 Make sure to enable the Google Apps Script API (as explained above) and perform a `clasp login` (with your specific login parameters) before you use the extension.
 
+### Installing as a Claude Code CLI Extension
+
+You can use clasp with Claude Code CLI in one of two ways:
+
+#### 1. Install as a Plugin (Recommended)
+
+Run the following command in Claude Code to install clasp as a plugin directly from the repository:
+
+```sh
+/plugin install @google/clasp
+```
+
+#### 2. Manual Installation
+
+You can manually add clasp as an MCP server using the provided configuration file or by running:
+
+```sh
+claude mcp add clasp -- npx -y @google/clasp mcp
+```
+
+Or by referencing the configuration file included in the repository:
+
+```sh
+claude mcp add-json clasp "$(cat claude-mcp.json)"
+```
+
 ## Commands
 
 The following command provide basic Apps Script project management.

claude-mcp.json

@@ -0,0 +1,8 @@
+{
+  "mcpServers": {
+    "clasp": {
+      "command": "npx",
+      "args": ["-y", "@google/clasp", "mcp"]
+    }
+  }
+}