feat: improve editor tooling and fix warnings

Neovim improvements:
- Add tree-sitter text objects for functions, types, blocks
- Add folding support
- Enhanced REPL integration (toggle, send line/selection)
- New commands: LuxCheck, LuxReplToggle, LuxSend
- Better keybindings with localleader

VS Code extension:
- Full syntax highlighting with TextMate grammar
- LSP client integration
- 20+ snippets for common patterns
- Commands: run, format, check, REPL
- Keybindings and context menu

Fixes:
- Fix all cargo warnings with #[allow(dead_code)] annotations
- Clean up unused variables

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

editors/vscode/README.md

@@ -0,0 +1,152 @@
+# Lux Language Extension for VS Code
+
+Visual Studio Code extension for the Lux programming language.
+
+## Features
+
+- **Syntax Highlighting**: Full syntax highlighting for Lux files
+- **LSP Integration**: Real-time diagnostics, hover info, completions, go-to-definition
+- **Snippets**: Common code patterns (functions, types, effects, handlers)
+- **REPL Integration**: Start REPL and send code to it
+- **Commands**: Run, format, type-check files
+
+## Installation
+
+### From VS Code Marketplace
+
+Search for "Lux Language" in the VS Code extensions panel.
+
+### From Source
+
+1. Clone the repository
+2. Navigate to `editors/vscode`
+3. Run `npm install`
+4. Run `npm run compile`
+5. Press F5 to launch a development VS Code window
+
+### Manual VSIX Install
+
+```bash
+cd editors/vscode
+npm install
+npm run compile
+npx vsce package
+code --install-extension lux-lang-0.1.0.vsix
+```
+
+## Requirements
+
+- **Lux binary**: Install Lux and ensure `lux` is in your PATH, or configure `lux.lspPath`
+- **Node.js**: For development
+
+## Configuration
+
+| Setting | Default | Description |
+|---------|---------|-------------|
+| `lux.lspPath` | `""` | Path to Lux binary. Empty = search PATH |
+| `lux.lsp.enabled` | `true` | Enable the language server |
+| `lux.format.onSave` | `false` | Format files on save |
+| `lux.diagnostics.enabled` | `true` | Show inline diagnostics |
+
+## Commands
+
+| Command | Keybinding | Description |
+|---------|------------|-------------|
+| `Lux: Run Current File` | `Ctrl+Shift+R` | Run the active file |
+| `Lux: Format Document` | - | Format the active file |
+| `Lux: Type Check File` | - | Type check without running |
+| `Lux: Start REPL` | - | Open Lux REPL in terminal |
+| `Lux: Send Selection to REPL` | `Ctrl+Enter` | Send selected code to REPL |
+| `Lux: Restart Language Server` | - | Restart the LSP |
+
+## Snippets
+
+| Prefix | Description |
+|--------|-------------|
+| `fn` | Function definition |
+| `fne` | Function with effects |
+| `type` | Type definition |
+| `effect` | Effect definition |
+| `handler` | Effect handler |
+| `match` | Match expression |
+| `if` | If expression |
+| `let` | Let binding |
+| `run` | Run with handlers |
+| `trait` | Trait definition |
+| `impl` | Impl block |
+| `matchopt` | Match on Option |
+| `matchres` | Match on Result |
+| `print` | Console.print |
+| `main` | Main function template |
+
+## Language Features
+
+### Syntax Highlighting
+
+- Keywords (`fn`, `let`, `type`, `effect`, `handler`, `match`, etc.)
+- Built-in types (`Int`, `Float`, `Bool`, `String`, `Option`, `Result`)
+- Operators (`=>`, `|>`, `==`, etc.)
+- String interpolation
+- Comments (line `//` and doc `///`)
+
+### LSP Features
+
+The Lux language server provides:
+
+- **Diagnostics**: Real-time error and warning display
+- **Hover**: Type information on hover
+- **Completions**: Context-aware suggestions
+- **Go to Definition**: Navigate to definitions
+
+### Code Folding
+
+Fold:
+- Function bodies
+- Type definitions
+- Effect declarations
+- Handler blocks
+- Match expressions
+
+## Development
+
+```bash
+# Install dependencies
+npm install
+
+# Compile
+npm run compile
+
+# Watch mode
+npm run watch
+
+# Lint
+npm run lint
+
+# Package
+npx vsce package
+```
+
+## Troubleshooting
+
+### LSP not starting
+
+1. Check `lux.lspPath` is correct
+2. Ensure `lux` binary is executable
+3. Run `Lux: Restart Language Server`
+4. Check Output panel for errors
+
+### No syntax highlighting
+
+1. Ensure file has `.lux` extension
+2. Try reloading VS Code
+
+## Contributing
+
+1. Fork the repository
+2. Create a feature branch
+3. Make changes
+4. Submit a pull request
+
+## License
+
+MIT License - see the main Lux repository for details.