Fix devcontainer build issues and add CI test workflow

- Remove PowerShell feature from default devcontainer (not needed, may cause timeouts)
- Fix updateContentCommand path to 'cd vscode-extension && npm ci' (repo structure changed)
- Add test-devcontainer.yml workflow to validate devcontainer builds in CI
- Update devcontainer-local.json with correct npm ci path

Agent-Logs-Url: https://github.com/rajbos/github-copilot-token-usage/sessions/a38744a9-240d-4e23-b4d8-b0344072c15c

Co-authored-by: rajbos <6085745+rajbos@users.noreply.github.com>

Author: Copilot

.devcontainer/devcontainer-local.json

@@ -33,6 +33,6 @@
   "containerEnv": {
     "NODE_OPTIONS": "--max-old-space-size=4096"
   },
-  "updateContentCommand": "npm ci",
+  "updateContentCommand": "cd vscode-extension && npm ci",
   "remoteUser": "node"
 }

.devcontainer/devcontainer.json

@@ -2,8 +2,7 @@
   "name": "Copilot Token Tracker Extension",
   "image": "mcr.microsoft.com/devcontainers/typescript-node:1-22-bookworm",
   "features": {
-    "ghcr.io/devcontainers/features/git:1": {},
-    "ghcr.io/devcontainers/features/powershell:1": {}
+    "ghcr.io/devcontainers/features/git:1": {}
   },
   "customizations": {
     "vscode": {
@@ -27,6 +26,6 @@
   "containerEnv": {
     "NODE_OPTIONS": "--max-old-space-size=4096"
   },
-  "updateContentCommand": "npm ci",
+  "updateContentCommand": "cd vscode-extension && npm ci",
   "remoteUser": "node"
 }

.github/workflows/test-devcontainer.yml

@@ -0,0 +1,52 @@
+name: Test DevContainer
+
+on:
+  push:
+    branches: [ main, develop, copilot/fix-codespace-boot-issue ]
+    paths:
+      - '.devcontainer/**'
+      - '.github/workflows/test-devcontainer.yml'
+  pull_request:
+    branches: [ main, develop ]
+    paths:
+      - '.devcontainer/**'
+      - '.github/workflows/test-devcontainer.yml'
+  workflow_dispatch:
+
+permissions:
+  contents: read
+
+jobs:
+  test-devcontainer:
+    runs-on: ubuntu-latest
+    
+    steps:
+    - name: Harden the runner (Audit all outbound calls)
+      uses: step-security/harden-runner@fa2e9d605c4eeb9fcad4c99c224cee0c6c7f3594 # v2.16.0
+      with:
+        egress-policy: audit
+
+    - name: Checkout code
+      uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
+      
+    - name: Build and test devcontainer
+      uses: devcontainers/ci@a56d055efecd725e8cfe370543b6071b79989cc8 # v0.3
+      with:
+        imageName: ghcr.io/${{ github.repository }}/devcontainer
+        cacheFrom: ghcr.io/${{ github.repository }}/devcontainer
+        push: never
+        runCmd: |
+          echo "=== DevContainer Environment Test ==="
+          echo "Node version: $(node --version)"
+          echo "NPM version: $(npm --version)"
+          echo "Working directory: $(pwd)"
+          echo "User: $(whoami)"
+          echo ""
+          echo "=== Installing dependencies ==="
+          cd /workspaces/github-copilot-token-usage/vscode-extension
+          npm ci
+          echo ""
+          echo "=== Running build ==="
+          npm run compile
+          echo ""
+          echo "=== DevContainer test successful ==="