add El LSP skeleton — language server, VSCode extension, syntax highlighting

Implements a Language Server Protocol server for El files over stdin/stdout
JSON-RPC. Provides completions (builtins + keywords + document functions),
hover documentation, go-to-definition, and full document sync.

Also adds a VSCode extension that launches the binary as a child process and
a TextMate grammar for .el syntax highlighting.

NOTE: el-lsp.el calls __read_n(n: Int) -> String, a seed primitive not yet
in el_runtime.c. Build.sh documents the required C implementation; the seed
agent must add it before the binary will link.

tools/lsp/vscode-extension/package.json

@@ -0,0 +1,55 @@
+{
+  "name": "el-language",
+  "displayName": "El Language",
+  "description": "El language support — syntax highlighting, completions, hover, go-to-definition",
+  "version": "0.1.0",
+  "publisher": "neuron-technologies",
+  "license": "MIT",
+  "engines": {
+    "vscode": "^1.75.0"
+  },
+  "categories": [
+    "Programming Languages"
+  ],
+  "keywords": [
+    "el",
+    "el-lang",
+    "language-server"
+  ],
+  "activationEvents": [
+    "onLanguage:el"
+  ],
+  "contributes": {
+    "languages": [
+      {
+        "id": "el",
+        "aliases": [
+          "El",
+          "el"
+        ],
+        "extensions": [
+          ".el"
+        ],
+        "configuration": "./language-configuration.json"
+      }
+    ],
+    "grammars": [
+      {
+        "language": "el",
+        "scopeName": "source.el",
+        "path": "./syntaxes/el.tmGrammar.json"
+      }
+    ]
+  },
+  "main": "./extension.js",
+  "dependencies": {
+    "vscode-languageclient": "^8.1.0"
+  },
+  "devDependencies": {
+    "@types/vscode": "^1.75.0"
+  },
+  "scripts": {
+    "vscode:prepublish": "echo 'no build step required'",
+    "package": "vsce package"
+  }
+}