Feature Request: Add Dart/Flutter LSP support

Summary

Add official Dart/Flutter language server support to Claude Code's LSP plugin system.

Motivation

Flutter is one of the most popular cross-platform mobile development frameworks, and Dart is its programming language. Currently, Claude Code supports LSP for many languages (TypeScript, Swift, Python, Go, Rust, Java, Kotlin, C#, C/C++, PHP, Lua) but lacks Dart/Flutter support.

This limits code intelligence features (go-to-definition, find references, hover info, document symbols) when working on Flutter projects.

Proposed Solution

Add a dart-lsp plugin to claude-plugins-official that enables the built-in Dart Analysis Server, similar to how other LSP plugins work.

The Dart SDK includes a language server that can be invoked with:

dart language-server

Suggested Configuration

{
  "dart": {
    "command": "dart",
    "args": ["language-server"],
    "extensionToLanguage": {
      ".dart": "dart"
    }
  }
}

Prerequisites

Users would need the Dart SDK or Flutter SDK installed, which includes the Dart language server.

Alternatives Considered

Attempted using a third-party plugin (dart-analyzer@claude-code-lsps), but Claude Code only supports built-in LSP implementations - external plugins can enable them but not add new language servers.

Additional Context

• Dart SDK: https://dart.dev/get-dart
• Flutter SDK: https://flutter.dev/docs/get-started/install
• Dart Language Server Protocol: https://github.com/dart-lang/sdk/blob/main/pkg/analysis_server/doc/lsp.md