Add MCP server project exposing DAX formatting over stdio

[marcosqlbi]

Summary

• New Dax.Formatter.McpServer project (net8.0) — a thin Model Context Protocol server over stdio that wraps DaxFormatterClient, so LLM clients (Claude Desktop, Claude Code, etc.) can format DAX via the existing daxformatter.com endpoints.
• Exposes two tools: format_dax (single expression) and format_dax_batch (multiple expressions), both accepting optional formatting options (listSeparator, decimalSeparator, maxLineLength, skipSpaceAfterFunctionName) and server metadata (serverType, serverMode, serverEdition, serverLocation, serverVersion, databaseCompatibilityLevel, serverName, databaseName). Enum params accept string names and produce a descriptive error on invalid values.
• Added the new project to src/Dax.Formatter.sln.

Test plan

• dotnet build src/Dax.Formatter.McpServer/Dax.Formatter.McpServer.csproj -c Debug — 0 warnings / 0 errors.
• JSON-RPC smoke test (initialize + tools/call format_dax) round-trips formatted DAX from the live daxformatter.com service.
• Invalid enum value (serverType:"NotAType") surfaces as an MCP tool error with allowed values listed.
• Wire up in an MCP client (Claude Desktop config) and exercise from a real chat session.

MCP client config

{
  "mcpServers": {
    "dax-formatter": {
      "command": "dotnet",
      "args": ["run", "--project", "<repo>/src/Dax.Formatter.McpServer", "-c", "Release", "--no-build"]
    }
  }
}

🤖 Generated with Claude Code