Add MCP server (stdio + HTTP) reusing the skill's Graph client

New mcp-server/ exposes SharePoint Lists as MCP tools (test, list_lists, get_columns, list_items, get_item, create/update/delete_item) via the same graph.mjs core. Supports stdio (Claude Desktop/Code/Cowork) and Streamable HTTP (--http). SP_READONLY gates write tools. Adds project .mcp.json and ignores build artifacts. Verified end-to-end live over stdio and HTTP initialize.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

.mcp.json

@@ -0,0 +1,8 @@
+{
+  "mcpServers": {
+    "sharepoint-lists": {
+      "command": "node",
+      "args": ["mcp-server/index.mjs"]
+    }
+  }
+}