STDIO initialize reports the mcp library version instead of the package version #128

The STDIO initialize reply's serverInfo.version reports the mcp library version (for example 1.30.0) instead of the index-it-mcp package version (for example 1.5.1). It's cosmetic, but clients and logs show the wrong version. Found during delivered acceptance of 1.5.1.

Fix: set the server's version from mcp_server.__version__ when constructing the MCP server, and add a test that the initialize reply carries the package version.