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/language-configuration.json

@@ -0,0 +1,53 @@
+{
+  "comments": {
+    "lineComment": "//",
+    "blockComment": ["/*", "*/"]
+  },
+  "brackets": [
+    ["{", "}"],
+    ["[", "]"],
+    ["(", ")"],
+    ["<", ">"]
+  ],
+  "autoClosingPairs": [
+    { "open": "{", "close": "}" },
+    { "open": "[", "close": "]" },
+    { "open": "(", "close": ")" },
+    { "open": "<", "close": ">", "notIn": ["string"] },
+    { "open": "\"", "close": "\"", "notIn": ["string"] },
+    { "open": "'", "close": "'", "notIn": ["string", "comment"] }
+  ],
+  "surroundingPairs": [
+    { "open": "{", "close": "}" },
+    { "open": "[", "close": "]" },
+    { "open": "(", "close": ")" },
+    { "open": "<", "close": ">" },
+    { "open": "\"", "close": "\"" },
+    { "open": "'", "close": "'" }
+  ],
+  "folding": {
+    "markers": {
+      "start": "^\\s*//\\s*#?region\\b",
+      "end": "^\\s*//\\s*#?endregion\\b"
+    }
+  },
+  "wordPattern": "[a-zA-Z_][a-zA-Z0-9_]*",
+  "indentationRules": {
+    "increaseIndentPattern": "^.*\\{[^}]*$|^.*\\([^)]*$|^.*\\[[^\\]]*$|^\\s*(fn|type|effect|handler|trait|impl|match|if|else)\\b.*$",
+    "decreaseIndentPattern": "^\\s*[}\\])]"
+  },
+  "onEnterRules": [
+    {
+      "beforeText": "^\\s*///.*$",
+      "action": { "indent": "none", "appendText": "/// " }
+    },
+    {
+      "beforeText": ".*\\{\\s*$",
+      "action": { "indent": "indent" }
+    },
+    {
+      "beforeText": "^\\s*\\}\\s*$",
+      "action": { "indent": "outdent" }
+    }
+  ]
+}