feat(cli): add VS Code extension wrapping glint lsp

editors/vscode/ is a TypeScript VS Code extension that starts glint lsp
as a child process and connects to it via vscode-languageclient. The
documentSelector restricts LSP processing to **/.gitlab-ci.yml so other
YAML files are unaffected. The glint.executablePath setting controls the
binary location (default: glint on PATH). Build with task ext-compile;
package as .vsix with task ext-package. Taskfile tasks added:
ext-install, ext-compile, ext-package. Root .gitignore updated to
exclude node_modules/, out/, and *.vsix from the extension directory.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

editors/vscode/tsconfig.json

@@ -0,0 +1,15 @@
+{
+  "compilerOptions": {
+    "module": "commonjs",
+    "target": "ES2020",
+    "lib": ["ES2020"],
+    "outDir": "out",
+    "rootDir": "src",
+    "strict": true,
+    "sourceMap": true,
+    "esModuleInterop": true,
+    "skipLibCheck": true
+  },
+  "include": ["src"],
+  "exclude": ["node_modules", "out"]
+}