feat: add devtools (tree-sitter, neovim, formatter, CLI commands)

- Add tree-sitter grammar for syntax highlighting
- Add Neovim plugin with syntax, LSP integration, and commands
- Add code formatter (lux fmt) with check mode
- Add CLI commands: fmt, check, test, watch, init
- Add project initialization with lux.toml template

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

editors/tree-sitter-lux/queries/locals.scm

@@ -0,0 +1,21 @@
+; Scopes
+(function_declaration) @scope
+(block_expression) @scope
+(lambda_expression) @scope
+(match_arm) @scope
+(handler_declaration) @scope
+
+; Definitions
+(function_declaration name: (identifier) @definition.function)
+(let_declaration name: (identifier) @definition.var)
+(parameter name: (identifier) @definition.parameter)
+(type_declaration name: (identifier) @definition.type)
+(effect_declaration name: (identifier) @definition.type)
+(trait_declaration name: (identifier) @definition.type)
+(handler_declaration name: (identifier) @definition.function)
+
+; Pattern bindings
+(pattern (identifier) @definition.var)
+
+; References
+(identifier) @reference