fix(ci): correct working-directory for extension npm ci step

The 'Install extension dependencies' step was using working-directory: .
(repo root) which has no package.json. Changed to vscode-extension/ where
the actual package.json lives.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: rajbos

.github/workflows/cli-publish.yml

@@ -58,7 +58,7 @@ jobs:
 
       - name: Install extension dependencies
         run: npm ci
-        working-directory: .
+        working-directory: vscode-extension
 
       - name: Install CLI dependencies
         run: npm ci