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>

Taskfile.yml

@@ -192,6 +192,22 @@ tasks:
     desc: "Preview unreleased changelog entries without writing (requires git-cliff)"
     cmd: git cliff --config cliff.toml --unreleased
 
+  ext-install:
+    desc: Install VS Code extension npm dependencies (run once after checkout)
+    dir: editors/vscode
+    cmd: npm install
+
+  ext-compile:
+    desc: Compile the VS Code extension TypeScript source
+    dir: editors/vscode
+    cmd: npm run compile
+
+  ext-package:
+    desc: Package the VS Code extension into a .vsix file
+    dir: editors/vscode
+    deps: [ext-compile]
+    cmd: npm run package
+
   clean:
     desc: Remove build artifacts
     cmd: rm -f {{.BINARY}} {{.BINARY}}-*.exe {{.BINARY}}-*-linux-amd64